Weight Reduction

"Endurance activities actually teach your body to store fat, sprinting teaches it to burn fat.

Not only that, but in a series of elegant experiments comparing interval training (10 times 30 seconds sprints with one minute rest in between), to constant state one hour aerobic activity, at the end of 12 weeks, the sprinters had lost more fat, gained more muslce, AND had higher VO2 max than the aerobic group…running was more effective than biking, but both benefitted from interval training more than the aerobic group."

Hi Lynn,
I'm trying to wrap my head around these assertions. Could you assist me by supplying some references?
I'm having particular trouble understanding how 30 second intervals, which are essentially an anaerobic exercise;
1) teach the body to burn fat, which requires copious amounts of oxygen to metabolize;
2) Develop a higher VO2 max when very little oxygen is required to complete the sprint.
My understanding is that sprinters up to 400(800?) meters rely initially on stored ATP and Creatine PO4, where energy is released by enzymatic processes that require no oxygen. Thereafter, incomplete oxidation of glucose supplies most of the remaining energy, with resulting buildup of lactate/lactic acid. This info is admittedly a couple of years old so, if you have newer research sources at your disposal, I'd sure appreciate your passing them on.
Cheers,
Tom

There is so much research pointing to the recovery period from training as being as much, if not more important in energy use, that I don't know where to begin. And it's not exactly new research (hint hint, bodybuilders have been using this knowledge for a long time to get very lean without losing muscle). For instance:

Postexercise energy expenditure and substrate oxidation in young women resulting from exercise bouts of different intensity.
Phelain JF, Reinke E, Harris MA, Melby CL.

Department of Food Science and Human Nutrition, Colorado State University, Ft. Collins 80523, USA.

OBJECTIVE: The effects of low and high intensity exercise, of similar energy output, on exercise and post-exercise energy expenditure and substrate oxidation were studied in eight active, eumenorrheic females (aged 22 to 31). METHODS: Continuous indirect calorimetry was performed during cycle ergometry exercise and for 3 hours following each of the following three protocols administered in random order: 1) low intensity exercise (LIE: 500 calories 50% VO2 max), 2) high intensity exercise (HIE: 500 calories 75% VO2 max), and 3) control condition (C) of quiet sitting for 1 hour, rather than exercise. Excess postexercise oxygen consumption (EPOC), energy expenditure and total fat and carbohydrate oxidation for the entire exercise/control plus 3-hour recovery period were determined by indirect calorimetry. RESULTS: Mean EPOC for the 3-hour post-exercise period for HIE was significantly greater than EPOC for low intensity exercise. Oxygen consumption (VO2) following HIE, but not LIE remained elevated at the end of the 3-hour post-exercise period. Total carbohydrate oxidation (exercise plus postexercise period) was significantly higher for HIE (116 +/- 8.6 g) compared to LIE (85.0 +/- 5.2 g). At the end of the 3-hour recovery period, the rate of fat oxidation was higher following HIE compared to LIE. CONCLUSION: These data indicate that the recovery period should also be considered when determining the impact of different exercise intensities on total energy expenditure and fat and carbohydrate utilization in women.

Effect of Exercise Training Intensity on Abdominal Visceral Fat and Body Composition.
Irving BA, Davis CK, Brock DW, Weltman JY, Swift D, Barrett EJ, Gaesser GA, Weltman A.

1Departments of Human Services, 2Internal Medicine, Division of Endocrinology and Metabolism, 3Pediatrics, Division of Cardiovascular Medicine, 4General Clinical Research Center, and 5Center for the Study of Complementary and Alternative Therapies, University of Virginia, Charlottesville, VA.

The metabolic syndrome is a complex clustering of metabolic defects associated with physical inactivity, abdominal adiposity, and aging. PURPOSE:: To examine the effects of exercise training intensity on abdominal visceral fat (AVF) and body composition in obese women with the metabolic syndrome. METHODS:: Twenty-seven middle-aged obese women (mean +/- SD; age = 51 +/- 9yr and body mass index = 34 +/- 6 kg.m) with the metabolic syndrome completed one of three 16-wk aerobic exercise interventions: (i) no-exercise training (Control): seven participants maintained their existing levels of physical activity; (ii) low-intensity exercise training (LIET): 11 participants exercised 5 d.wk at an intensity LT and 2 d.wk LT. Exercise time was adjusted to maintain caloric expenditure (400 kcal per session). Single-slice computed tomography scans obtained at the L4-L5 disc space and midthigh were used to determine abdominal fat and thigh muscle cross-sectional areas. Percent body fat was assessed by air displacement plethysmography. RESULTS:: HIET significantly reduced total abdominal fat (P < 0.001), abdominal subcutaneous fat (P = 0.034), and AVF (P = 0.010). There were no significant changes observed in any of these parameters within the Control or the LIET conditions. CONCLUSIONS:: The present data indicate that body composition changes are affected by the intensity of exercise training with HIET more effectively for reducing total abdominal fat, subcutaneous abdominal fat, and AVF in obese women with the metabolic syndrome.

Aerobic interval training versus continuous moderate exercise as a treatment for the metabolic syndrome: a pilot study.
Tjønna AE, Lee SJ, Rognmo Ø, Stølen TO, Bye A, Haram PM, Loennechen JP, Al-Share QY, Skogvoll E, Slørdahl SA, Kemi OJ, Najjar SM, Wisløff U.

Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.

BACKGROUND: Individuals with the metabolic syndrome are 3 times more likely to die of heart disease than healthy counterparts. Exercise training reduces several of the symptoms of the syndrome, but the exercise intensity that yields the maximal beneficial adaptations is in dispute. We compared moderate and high exercise intensity with regard to variables associated with cardiovascular function and prognosis in patients with the metabolic syndrome. METHODS AND RESULTS: Thirty-two metabolic syndrome patients (age, 52.3+/-3.7 years; maximal oxygen uptake [o(2)max], 34 mL x kg(-1) x min(-1)) were randomized to equal volumes of either moderate continuous moderate exercise (CME; 70% of highest measured heart rate [Hfmax]) or aerobic interval training (AIT; 90% of Hfmax) 3 times a week for 16 weeks or to a control group. o(2)max increased more after AIT than CME (35% versus 16%; P<0.01) and was associated with removal of more risk factors that constitute the metabolic syndrome (number of factors: AIT, 5.9 before versus 4.0 after; P<0.01; CME, 5.7 before versus 5.0 after; group difference, P<0.05). AIT was superior to CME in enhancing endothelial function (9% versus 5%; P<0.001), insulin signaling in fat and skeletal muscle, skeletal muscle biogenesis, and excitation-contraction coupling and in reducing blood glucose and lipogenesis in adipose tissue. The 2 exercise programs were equally effective at lowering mean arterial blood pressure and reducing body weight (-2.3 and -3.6 kg in AIT and CME, respectively) and fat. CONCLUSIONS: Exercise intensity was an important factor for improving aerobic capacity and reversing the risk factors of the metabolic syndrome. These findings may have important implications for exercise training in rehabilitation programs and future studies.

Interpreting energy expenditure for anaerobic exercise and recovery: an anaerobic hypothesis.
Scott CB.

Heart and Lung Group of Savannah, Georgia 31405, USA.

Energy expenditure during and after exercise is composed of aerobic and anaerobic bioenergetics and the energy demands of aerobic recovery. Current attempts to measure energy expenditure include an exercise oxygen uptake + oxygen debt (EPOC) measurement or, an oxygen deficit + exercise oxygen uptake measurement. This investigation illustrates how oxygen debt and oxygen deficit interpretation can effect a total energy expenditure measurement. It was hypothesized that the total energy expenditure for several intermittent bouts of exercise and recovery would be greater than for one bout of continuous exercise and recovery when equivalent work was compared. Exercise was performed under low-intensity and high-intensity conditions. Both oxygen debt and oxygen deficit methodology resulted in similar energy expenditure measurements for both intermittent and continuous exercise. This implies little to no recovery energy demand or considerable methodology errors. Differences in total energy expenditure were found when the oxygen deficit and parts of the oxygen debt (EPOC) were considered separate and independent (p < 0.05). These differences can be accounted for when the data are interpreted utilizing thermodynamic (2nd law) and engineering (in-series efficiency) concepts rather than the heat equivalent of carbohydrate oxidation (20.9 kJ equals one liter of O2). It is suggested that while oxygen uptake provides an excellent representation of aerobic metabolism during exercise and recovery, oxygen uptake may be an inadequate measure of the energetics of lactate production (fermentation). In application, energy expenditure differences appear realistic only for high-intensity, intermittent exercise rather than lower intensity exercise.

Effects of high intensity / low volume and low intensity / high volume isokinetic resistance exercise on postexercise glucose tolerance.
Miller AD, Ruby BC, Laskin JJ, Gaskill SE.

Human Performance Laboratory, The University of Montana, Missoula, Montana 59812, USA.

The purpose of this study was to determine the effects of high intensity/ low volume (HILV) and low intensity/high volume (LIHV) isokinetic resistance exercise on postexercise glucose tolerance. Subjects (n = 10) participated in a counterbalanced, randomized design of 2 separate isokinetic resistance exercise trials (HILV and LIHV) of reciprocal concentric knee flexion and knee extension in a fasted state. Each bout was followed by a 45-minute oral glucose tolerance test (OGTT; 1.8 g.kg fat free mass(-1)). Blood samples were obtained every 15 minutes to determine glucose and insulin concentrations. There was no difference in total work between the 2 trials (p = 0.229). Blood glucose was significantly higher at all time points compared with time 0 following the LIHV trial (p < 0.05). Following the HILV trial, blood glucose was significantly elevated at 15 and 30 minutes (p < 0.05), but returned to resting values by 45 minutes. Insulin concentration was significantly elevated following both trials at all time points (p < 0.05). Blood glucose and insulin were significantly higher following the LIHV at 30 and 45 minutes compared with the HILV trial (p < 0.05). These results demonstrate that although the total work output was similar across trials, high intensity muscle contraction is associated with an enhanced normalization of glucose homeostasis following a large postexercise oral glucose feed

Effect of exercise intensity and duration on postexercise energy expenditure.
Sedlock DA, Fissinger JA, Melby CL.

Exercise Physiology Laboratory, Purdue University, West Lafayette, IN 47907.

The purpose of this study was to examine 1) the effect of two exercise intensities of equal caloric output on the magnitude (kcal) and duration of excess postexercise oxygen consumption (EPOC) and 2) the effect of exercise of equal intensity but varying duration on EPOC. Ten trained male triathletes performed three cycle ergometer exercises: high intensity-short duration (HS), low intensity-short duration (LS), and low intensity-long duration (LL). Baseline VO2 was measured for 1 h prior to each exercise condition. Postexercise VO2 was measured continuously until baseline VO2 was achieved. The duration of EPOC was similar for HS (33 +/- 10 min) and LL (28 +/- 14 min), and both were significantly longer (P less than 0.05) than the EPOC following LS (20 +/- 5 min). However, total net caloric expenditure was significantly more (P less than 0.05) for HS (29 +/- 8 kcal) than for either LS (14 +/- 6 kcal) or LL (12 +/- 7 kcal). The exercise conditions used in this study did not produce a prolonged EPOC. However, the exercise intensity was shown to affect both the magnitude and duration of EPOC, whereas the exercise duration affected only the duration of EPOC. Moreover, the duration of EPOC and the subsequent caloric expenditure were not necessarily related. Based on the resulting magnitude of the postexercise energy expenditure, it is possible that EPOC may be of some value for weight control over the long term.

Lacour JR.

Laboratoire de physiologie de l'exercice, EA 645 Faculté de médecine Lyon-Sud F-69921 Oullins. lacour@univ-lyon1.fr

A high level of physical activity is associated with a lower cardiovascular risk in adult and elderly subjects. Several mechanisms are involved. Physical activity induces an increase in energy output. The contribution of fats to muscle energy metabolism increases with exercise duration. It decreases with exercise intensity. EPOC contributes by about 10% to the total energy cost of exercise. This supplementary energy expenditure is principally covered with fat oxidation, this being related to GH release. Part of energy expended during intermittent exercise is supplied by fat oxidation. The used lipids are taken from the muscular triacylglycerol stores and from the circulating FFA and lipoprotein triacylglycerols. Hydrolysis of triacylglycerols is achieved by LPL. Endurance training induces an increased contribution from fat to the exercise energy need. This results from increased muscle capillary density, enhanced activity of LPL and of the enzymes controlling beta-oxydation. The increased energy expenditure results in a reduced fat mass, which accounts for a decreased plasma triacylglycerol level. Endurance activity requiring approximately an expenditure of 60 kJ.kg-1 per week usually produces favourable lipoprotein changes. Level of post-prandial lipemia is lowered. These alterations disappear within the first two days of recovery.

Comparison of energy expenditure elevations after submaximal and supramaximal running.
Laforgia J, Withers RT, Shipp NJ, Gore CJ.

Exercise Physiology Laboratory, School of Education, Flinders University of South Australia, Adelaide, Australia.

Although exercise intensity has been identified as a major determinant of the excess postexercise oxygen consumption (EPOC), no studies have compared the EPOC after submaximal continuous running and supramaximal interval running. Eight male middle-distance runners [age = 2.1 +/- 3.1 (SD) yr; mass = 67.8 +/- 5.1 kg; maximal oxygen consumption (VO2max) = 69.2 +/- 4.0 ml.kg-1.min-1] therefore completed two equated treatments of treadmill running (continuous running: 30 min at 70% VO2max; interval running: 20 x 1-min intervals at 105% VO2max with intervening 2-min rest periods) and a control session (no exercise) in a counter-balanced research design. The 9-h EPOC values were 6.9 +/- 3.8 and 15.0 +/- 3.3 liters (t-test:P = 0.001) for the submaximal and supramaximal treatments, respectively. These values represent 7.1 and 13.8% of the net total oxygen cost of both treatments. Notwithstanding the higher EPOC for supramaximal interval running compared with submaximal continuous running, the major contribution of both to weight loss is therefore via the energy expended during the actual exercise.

Effect of an acute period of resistance exercise on excess post-exercise oxygen consumption: implications for body mass management.
Schuenke MD, Mikat RP, McBride JM.

Present address: Department of Biological Sciences, Ohio University, 128 Irvine Hall, Athens, OH 45701, USA. mschuenke@hotmail.com

Studies have shown metabolism to remain elevated for hours following resistance exercise, but none have gone beyond 16 h, nor have they followed a whole body, high intensity exercise protocol. To examine the duration of excess post-exercise oxygen consumption (EPOC) following a period of heavy resistance exercise, seven healthy men [mean (SD) age 22 (3) years, height 177 (8) cm, mass 83 (10) kg, percentage body fat 10.4 (4.2)%] engaged in a 31 min period of resistance exercise, consisting of four circuits of bench press, power cleans, and squats. Each set was performed using the subject's own predetermined ten-repetition maximum and continued until failure. Oxygen consumption ( ) measurements were obtained at consistent times (34 h pre-, 29 h pre-, 24 h pre-, 10 h pre-, 5 h pre-, immediately post-, 14 h post-, 19 h post-, 24 h post-, 38 h post-, 43 h post-, and 48 h post-exercise). Post-exercise measurements were compared to the baseline measurements made at the same time of day. The was significantly elevated ( P<0.05) above baseline values at immediately post, 14, 19, and 38 h post-exercise. Mean daily values for both post-exercise days were also significantly elevated above the mean value for the baseline day. These results suggest that EPOC duration following resistance exercise extends well beyond the previously reported duration of 16 h. The duration and magnitude of the EPOC observed in this study indicates the importance of future research to examine a possible role for high intensity resistance training in a weight management program for various populations.

Ummm, that's for starters ;)

The effects of exercise intensity on body composition, weight loss, and dietary composition in women.
Bryner RW, Toffle RC, Ullrich IH, Yeater RA.

Department of Exercise Physiology, School of Medicine, West Virginia University, Morgantown, USA.

OBJECTIVE: There is controversy over whether exercise and/or exercise intensity has an effect on total caloric intake or diet composition. The purpose of this study was to test the effect of exercise intensity without dietary manipulation on body composition and/or weight loss and to determine whether exercise intensity affected total caloric intake or diet composition in normal weight young women. METHODS: Fifteen women aged 18 to 34 years with a maximal oxygen consumption average or below on the Palo Alto norms served as subjects. Subjects were randomly assigned to: 1) low heart rate intensity exercise group (LI, N = 7) which exercised 40 to 45 minutes approximately four times weekly at a mean heart rate of 132 beats per minute (bpm); 2) high heart rate intensity group (HI, N = 8) which exercised 40 to 45 minutes approximately four times weekly at a mean HR of 163 bpm. All subjects were given a maximal exercise test prior to and during weeks eight, 12 and 16. The first 4 weeks served as a control period, followed by approximately 11 weeks of exercise. Each subject recorded her dietary intake for 1 complete week, including a weekend, during weeks 2, 6, 10 and 14 of the study. RESULTS: VO2 max increased (p < .05) in HI (29 +/- 6 ml/kg/minute to 38 +/- 7) but did not change in LI (36 +/- 5 to 38 +/- 7). Percent fat decreased in HI (p < .05) (27 +/- 7 to 22 +/- 4) but was unchanged in LI (22 +/- 6 to 21 +/- 6). The weekly intake of total kcal, carbohydrate, protein and fat did change significantly for either group. The weekly intake of saturated fat declined significantly (p < .05) in HI (21.2 +/- 5.8 g to 14.9 +/- 5.5 g); their weekly intake of cholesterol also decreased (p < .05) between months 2 to 3 (249 +/- 109 mg to 159 +/- 58 mg). No other differences in dietary intake between groups were found. CONCLUSION: High heart rate intensity exercise training without dietary manipulation resulted in a decrease in body fat, but not weight change, as well as a decrease in the intake of saturated fat and cholesterol in normal weight young women. These changes were not observed after low heart rate intensity training.

The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women.
Trapp EG, Chisholm DJ, Freund J, Boutcher SH.

Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia. e.trapp@unsw.edu.au

OBJECTIVE: To determine the effects of a 15-week high-intensity intermittent exercise (HIIE) program on subcutaneous and trunk fat and insulin resistance of young women. DESIGN AND PROCEDURES: Subjects were randomly assigned to one of the three groups: HIIE (n=15), steady-state exercise (SSE; n=15) or control (CONT; n=15). HIIE and SSE groups underwent a 15-week exercise intervention. SUBJECTS: Forty-five women with a mean BMI of 23.2+/-2.0 kg m(-2) and age of 20.2+/-2.0 years. RESULTS: Both exercise groups demonstrated a significant improvement (P<0.05) in cardiovascular fitness. However, only the HIIE group had a significant reduction in total body mass (TBM), fat mass (FM), trunk fat and fasting plasma insulin levels. There was significant fat loss (P<0.05) in legs compared to arms in the HIIE group only. Lean compared to overweight women lost less fat after HIIE. Decreases in leptin concentrations were negatively correlated with increases in VO(2peak) (r=-0.57, P<0.05) and positively correlated with decreases in TBM (r=0.47; P<0.0001). There was no significant change in adiponectin levels after training. CONCLUSIONS: HIIE three times per week for 15 weeks compared to the same frequency of SSE exercise was associated with significant reductions in total body fat, subcutaneous leg and trunk fat, and insulin resistance in young women.

High-intensity or low intensity–working out in the morning will burn roughly twice as many calories as the same level and duration of exercise during the day (when not in a fasted state).

From my experience, I lean up the most quickly from morning exercise on an empty stomache….though the high-intensity vs. low-intensity debate is above my paygrade on this topic.

"OBJECTIVE: There is controversy over whether exercise and/or exercise intensity has an effect on total caloric intake or diet composition'

I can tell you there little controversy among serious athletes= short (under an hour) and intense trumps long and low every time.
short and intense is a work out, long and low is an "activity"

Thanks for the input, Lynn. I still don't quite understand how aerobic exercise teaches the body to store fat, nor do I understand how sprinters end up with higher VO2 max than distance runners. I am thinking of 5K to marathon distance when I say distance runners. Have any comparative studies been done of runners of equal quality from both groups?

Brian. With all due respect to those who engage in high intensity sports, relatively low intensity sports, like distance running, can be pretty demanding. Run a marathon sometime, and I don't mean jogging one. You'll know you've had a workout.

"High-intensity or low intensity–working out in the morning will burn roughly twice as many calories as the same level and duration of exercise during the day (when not in a fasted state)."

Interesting … I find that when I go to the gym, part of what determines the quality of the workout is whether I am light on food. The times I am light on food, I can feel that I am low on energy part way through my weights workout. I end up with lower weights, fewer reps or something along that line. Hard to believe I am burning twice the calories. I am certainly doing less physical work.

I find a similar thing hiking — I can go stronger when I fill my Platypus with a homemade Gatorade equivalent (OJ, salt and a carb mixture). Drinking that as I go sure has me hiking stronger. Again, empirically exercising when in a calorie-depleted state does not seem to work as well; it is hard to believe I am burning twice the calories that way.

'Run a marathon sometime, and I don't mean jogging one. You'll know you've had a workout."
Yes, but a marathon last longer than the body can produce a high a mount of testosterone to aid in muscle recovery, thus a marathon causes muscle cannibalism and not muscle gain. Its hard work no doubt but its not a "workout" in the sense that you are shocking the body to build up the body- its an endurance activity where one has to deal with a body that is breaking down.
Its the difference between someone forced to do hard work all day without adequate food and some one who traumatizes the body quickly in a short time and immediately gives the body the nutrition it needs and a long recovery rest.
The former will be lean, weak and tired and the other will be muscular and strong.
In other words running a marathon is intensity prolonged. Its not necessary or desirable from a strict health point of view its a sport about dealing with the body as it breaks down -a mental game.

There is no real scientific evidence that working out in the morning has any greater effect on calories burned or fat lost, although it was a popular conception a while back. It has also been disproven that exercising on an empty stomach has any advantages in this regard.

Endurance activities seem to promote fat storage because the nature of the 'activity' promotes a high degree of fat burning. The body learns that it needs to store readily mobilisable fat for future bouts of endurance. This is most drmatically seen when taking a group of endurance athletes and forcing them to be sedentary for 3 months. At the end of three months, they will have a blood lipid profile like someone with metabolic syndrome. The combination of teaching the body to use fat as a predominant fuel and having a small amount of muscle mass is a bad combination if you ever stop exercising.

VO2 max is elevated to a greater degree in sprint activities because it is an all out anearobic effort. This forces the body to adapt to extract every molecule of oxygen it can from the air during recovery. Bigger lungs, bigger heart, better circulation are needed.

But this is all pretty much academic. What is absolutely clear is that some exercise is better than none. Cross training seems to offer the most all around benefits for people wanting to do a range of activities, and weight loss is ultimately a matter of calories in < calories burned. Hiking is a great way to burn calories (I hope we are all in agreement on that one).

The internet and research are great–give me an hour and I'll find a study showing the advantages. It's been well proven–but putting aside academic research, if you want to lean up, exercise in the morning on an empty stomach for a short-duration/high intensity, and you'll be stunned with the results in a few weeks. So stunned that research proving to the contrary will be utterly meaningless to you.

I have to agree with Allison (or are you going by Lynn now?)The best exercise is the one you do.

and I might add the one that you do consisitently. If running in the morning on an empty stomach works for you, awesome (personally I would pass out) if its lifting weights on a nautilus machine and running on a treadmill, and you keep it up, awesome. There are tons of studeies out there and different ideas about what is best, but I think a lot of it is splitting hairs, especially if you aren't exercising. Go for a walk and don't eat more and you will lose weight.

Personally, I like to run. I do pushups and chinups most days and yoga a couple of times a week, and I hit the weightroom a couple of times a week to lift freeweights. I hang around 195-200 at 6'1" and can run a sub 4 marathon. It works for me, it might not work for you
DYOE (do your own exercise)

I like these academic debates. Understanding how things work in detail is fascinating.

But, as someone who has struggled with weight my entire life, the following quote from Nate is the key part:

"exercise… and you'll be stunned with results in a few weeks."

When I get regular exercise and eat reasonable quantities of healthy food I find I lose weight easily and steadily. I don't get too fussed on whether or not I'm hitting optimal efficiency. Just my 2c.

Effect of feeding and fasting on excess postexercise oxygen consumption.
Bahr R, Sejersted OM.

Department of Physiology, National Institute of Occupational Health, Oslo, Norway.

This study was undertaken to determine the effect of fasting on the magnitude and time course of the excess postexercise O2 consumption (EPOC). Six untrained subjects were studied in the fasted state for 7 h after a previous strenuous exercise bout, and in a control experiment. The results were compared with identical control and exercise experiments where the subjects were fed a 4.5-MJ test meal after 2 h of rest. EPOC was calculated as the difference in O2 uptake between the corresponding control and exercise experiments. The total EPOC (0-7 h postexercise) was 20.9 +/- 4.5 (fasting) and 21.1 +/- 3.6 liters (food, NS). A significant prolonged EPOC component was observed in the fasted and in the fed state. The thermic effect of food (TEF) was calculated from O2 consumption and respiratory exchange ratio as the difference in energy expenditure between the corresponding food and fasting experiments. The total TEF (0-5 h postprandial) was 321 +/- 32.0 (control) and 280 +/- 37.7 kJ/5 h (exercise, NS). It is concluded that the prolonged component of EPOC is present in the fasting state. Furthermore, no major interaction effects between food intake and exercise on the postexercise O2 consumption could be detected.

Compare this to:

Acute effects of exercise timing and breakfast meal glycemic index on exercise-induced fat oxidation.
Appl Physiol Nutr Metab. 2006 Oct;31(5):502-11.

Fat balance is an important determinant of energy balance. Exercise after an overnight fast can significantly increase fat oxidation; however, little information pertaining to the effects of exercise and meal glycemic index on fat oxidation under these conditions is available. The objective of this investigation was to study the acute effects of exercise timing and meal glycemic index (GI) on whole-body fat oxidation. Eight apparently healthy young men completed 4 randomly ordered trials during which measurements were made at rest, during exercise, and for 2 h post-exercise and (or) post-prandial. After an overnight fast, subjects were required to perform 400 kcal of treadmill exercise (at FATmax) either before consuming a 400 kcal low-GI (Ex-LG) or high-GI (Ex-HG) oatmeal breakfast, or after consuming the low-GI (LG-Ex) or high-GI (HG-Ex) meal. The amount of fat oxidized during exercise was significantly greater during Ex-LG and Ex-HG (17.2 +/- 4.0 and 17.5 +/- 4.7 g, respectively) than during LG-Ex and HG-Ex (10.9 +/- 3.7 and 11.7 +/- 3.5 g, respectively) (p < 0.001), as was the amount of fat oxidized during the entire trial (Ex-LG: 23.4 +/- 4.7 g; Ex-HG: 23.4 +/- 6.5 g; LG-Ex: 18.4 +/- 4.7 g; HG-Ex: 19.6 +/- 4.9 g) (p < 0.05), even though energy expenditure was not different across experimental conditions. No significant effect of meal GI on the amount of fat oxidized was noted. Total fat oxidized during exercise, and for 2 h after exercise, was greatest when morning exercise was performed in the fasted state, independently of meal GI.

You will see that, although exercising in the morning results in an increase in fat burned (by a whopping 5 grams or 45 calories) over two hours, by 7 hours there is no difference in total energy burned. Most of the studies you will find showing a benefit to exercising first thing on an empty stomach look only at the short term fat burned, not the effect over a whole day. And even if there were a difference, at 45 calories it would take you 77 days to lose an extra pound.

>if you want to lean up, exercise in the morning on an empty stomach for a short-duration/high intensity, and you'll be stunned with the results in a few weeks

Yup. You will also be stunned if you do this in the evening, or at mid day. As with any high intensity exercise, you certainly can't do it on a full stomach, but it is not necessary to do it in a fasted state to reap the benefits. Just do it!

I ran the Boston Marathon in 2001 & was in possibly sub 3hour marathon shape as recently as early 2003 – ran the 2002 national xcountry championships (I wasn't last). I also ran a 50K (31 mile) race in 2001.

A series of health issues has meant no running for about 3.5 years – in which time I've gained over 40lbs (on a 5'5" frame) and my lipid profile is roughly on par with one for metabolic syndrome. I eat mostly vegetarian diet with some fish and occasional cheese or egg, very rarely have sweets – i do like beer.

I'd say my body was definitely trained to store away fat – I also suspect there is some genetic preference for the same. It's very, very hard for me to lose weight and very, very easy to gain. Even when I was running – I didn't thin down until I was consistently doing 40+ miles per week & I always included at least 2 speedwork sessions per week.

Interesting stuff.

I agree with Nate, BUT It doesn't have to be in the morning -its just that the body is coming off a fast and since most people break that fast first thing in the morning they wont have an empty stomach at any other time. So it follows that saying "work out in the morning" makes sense.
I dont eat breakfast personally, in fact I eat only one main meal a day usually- this allows my body to detoxify all day and "get ready" for a large meal at night -then the process is repeated.
Your nervous system is different on a fast than it is while eating. On a fast fat and mitochondria in muscle are used for energy, after eating your body uses that food as an easy quick energy source ( carbs etc).
note: after about 16-18 hours or so a fast will become a negative and the body will cannibalize muscle tissue and store fat like crazy, that time includes time sleeping (8 hours sleeping + 8 or 10 hours awake) so use it wisely.

Just to bring things back around more to the topic of weight reduction, I should point out that exercise alone rarely results in weight LOSS for most folks. Fitness and weight loss are two different processes. To lose weight, you need to eat less than you burn. Most people are terrible at this if they don't make a conscious effort to reduce their food intake. Exercise will make you healthier, and increase muscle mass while losing fat (if it's not an inherently muscle wasting extreme endurance exercise), but not result in weight loss.

Other factors also come into play. If you are not a morning person, then exercising in the morning just doens't make sense. Although I am a 'morning' person, my body is at it's peak around 10am, or roughly 4 hours after breakfast. This is plenty of time for me to have an empty enough stomach for intense exercise, and by waiting until 10am, I can train harder. YMMV. I seem to recall that the hormonal changes associated with puberty make most adolescents unfit for much of anything before noon!

I agree with Lynn's last comment. Exercise and weight loss are different things. In my experience, intense exercise does not result in weight loss. In fact, the opposite can be true in the short term because when I exercise at a high level, I do not have nearly the control over my eating that I otherwise have. Weight loss is about food. Take in 3500 less calories than you burn and you lose a pound. Without any additional exercise, that means having a piece of fruit instead of a candy bar for a snack each day to lose a pound in a month. And continuing to make healthy substitutions and choices and controlling portion size will cause you to continue to drop pounds and keep them off. Over time, this has resulted in large sustained weight loss for me. It involves lifestyle change; not dieting. That said, exercising at the level many of us do has many other benefits and I'm not knocking it. I'm just saying don't think going to the gym means you will lose weight. I did that for years; it wasn't until I ate better and less that I lost weight. (As Michael Pollan says, "Eat less, and mostly plants.")

I don't agree that it's a simple equation of 3500 fewer calories in = 1 lb lost.

I think some metabolisms are better at idling lower when there are fewer calories available & will become more efficient faster than others – I seem to have one of these.

My metabolism seems to adjust quickly to any decrease in calories to hold onto every possible calorie. Likewise, when more calories are available, it is very efficient at storing those calories away. I think this is partly or even largely genetic – must have been a lot of famine surviving peasants in my family tree. I think my background as a distance athlete also may have "trained" my body to be more efficient at keeping and using calories.

You must eat right AND exorcise. But there is exorcise to gain muscle mass and then there is exorcise to loss fat.
This is why in a traditional work out one would weight train for a month or two adding muscle and eating more calories which also usually added extra fat.
This is when one would enter the "lean out" phase and consume less calories and do aerobics for another month or two and this cycle will be repeated.
Of coarse these days there is 3rd way cardio which has revolutionized the athletic community as well as the Parrillo diet which has revolutionize the bodybuilding community.

You are right Cary, and this is where the exercise CAN make a difference. Your metabolism will want to slow down if you continually give it less food than it 'wants', but by gradually increasing your exercise level at the same time as dieting, you can stave this off. But some people just become worse and worse at losing weight. Yo-yo dieters have it the hardest, as they've basically trained their body to crave and store excess calories. I used to be really good at 'dieting' for bodybuilding shows, until a combo of middle age, injury and the effects of yo-yo dieting caught up with me. Now my body goes into starvation mode very quickly with even a small calorie deficit :(

One trick that works well for people like 'us' is to have regular "refeeds" Once or twice a week, eat a whole bunch of carbs and proteins…as many as you crave, but try to keep it low fat. This helps to keep your body out of starvation mode, and the metabolic boost from the extra calories over several days more than compensates for the total calories eaten in that meal.

I see this piece of research just came out. Interesting-15 minutes per day 3 times a week (4-6 sprints of 30 seconds each):

Extremely short duration high intensity training substantially improves insulin action in young sedentary males.
Babraj JA, Vollaard NB, Keast C, Guppy FM, Cottrell G, Timmons JA.
BMC Endocr Disord. 2009 Jan 28;9(1):3

ABSTRACT: BACKGROUND: Classic, long duration aerobic exercise reduces cardiovascular and metabolic disease risk but this involves a substantial time commitment. Extremely low volume high-intensity interval training (HIT) has recently been shown to cause similar improvements to aerobic performance, but it has not been established whether HIT has the capacity to improve glycemic control. METHODS: Sixteen young men (age: 21+/-2 y; BMI: 23.7+/-3.1 kg * m-2; VO2peak: 48+/-9 ml * kg-1 * min-1) performed 2 weeks of supervised HIT comprising of a total of 15 min of exercise (6 sessions; 4-6 x 30-s cycle sprints per session). Aerobic performance (250-kJ self-paced cycling time trial), and glucose, insulin and NEFA responses to a 75-g oral glucose load (oral glucose tolerance test; OGTT) were determined before and after training. RESULTS: Following 2 weeks of HIT, the area under the plasma glucose, insulin and NEFA concentration-time curves were all reduced (12%, 37%, 26% respectively, all P<0.001). Fasting plasma insulin and glucose concentrations remained unchanged, but there was a trend towards reduced fasting plasma NEFA concentrations post-training (pre: 350 +/- 36 v post: 290 +/- 39 mumol * l-1, P=0.058). Insulin sensitivity as measured by the Cederholm index was improved by 22.5% (P<0.01). Aerobic cycling performance was improved by ~6% (P<0.01). CONCLUSIONS: The efficacy of a high intensity exercise protocol, involving only ~250 kcal work each week, to substantially improve insulin action in young sedentary subjects is remarkable. We feel this novel time-efficient training paradigm can be used as a strategy to reduce metabolic risk factors in young and middle aged sedentary populations who otherwise would not adhere to a classic high volume, time consuming exercise regimes.

"Even when I was running – I didn't thin down until I was consistently doing 40+ miles per week & I always included at least 2 speedwork sessions per week."

Can anyone say how that would translate into day hiking or backpacking? Or — for the gym-bound — an elliptical exercise machine?

"The former will be lean, weak and tired and the other will be muscular and strong.
In other words running a marathon is intensity prolonged. Its not necessary or desirable from a strict health point of view its a sport about dealing with the body as it breaks down -a mental game."

Brian,
Runners, by the nature of their sport, do not aspire to bulk
up. It simply does not contribute to performance. A marathon does, indeed, break down the body which is why there is a recovery period after running one. But the race is only the culmination of a long period of training, "workouts" of various types blending together to build up the body to handle the race. The same is true of any athletic event and the more the event involves endurance, the greater the breakdown and recovery period. High altitude climbing and long distance backpacking are no different in that regard. Ask Roman and Jason, or any high altitude expedition climber. They all look skeletal coming off the mountain. But, do not confuse leanness with weakness. To be sure, some lean people are weak, and all endurance athletes are likely to be weak just after completing an event. But most well trained endurance athletes, climbers to be sure, and most distance runners as well, spend a lot of time developing upper body strength and have a very high strength to body weight ratio. Watch a "scrawny" climber float up an overhanging pitch, or muscle their way up an off width crack when necessary-a combination of technique AND strength. Ditto those frail distance runners cranking out sets of pullups. OTOH, I have seen many very muscled specimens struggle to do 10 pullups. My point is that different activities require different training protocols and tend to attract different body types/mindsets. All require varying proportions of strength, endurance, and technique if one is to be successful. A well trained athlete, no matter the event, is likely to possess all 3.

"The combination of teaching the body to use fat as a predominant fuel and having a small amount of muscle mass is a bad combination if you ever stop exercising."

This makes sense to me but why stop exercising? OTOH, I have seen a whole lot of lifters/body builders go to h$ll in a hand basket real quick when they stopped exercising. Go figure. I don't think that is peculiar to endurance athletes.

"VO2 max is elevated to a greater degree in sprint activities because it is an all out anearobic effort. This forces the body to adapt to extract every molecule of oxygen it can from the air during recovery. Bigger lungs, bigger heart, better circulation are needed."

So does exercising at the anaerobic threshold, which is why distance runners do a lot of interval training at or near that threshold but don't cross the line, which would just court injury. If you are saying that athletes who engage in anaerobic events have bigger lungs, bigger hearts, and better circulatory systems
than those who engage in endurance events, do you supporting data? World class Nordic skiers, high altitude climbers, and marathoners vs sprinters, hurdlers, etc would seem to be a logical comparison. Carl Lewis vs Haile Gebresellasie?? It just doesn't seem logical, Lynn. At the threshold does make a lot of sense. In fact, I once had a very interesting conversation with a physician who was on an Everest expedition. One of the things they were studying was which type of training background tended to do best at high altitude. Now, one expedition with a small number of participants is not definitive, but they found a couple of people stood out and they both had a middle distance running background-not marathoners as they had expected. Makes sense because running 5-10 km puts you near and at the anaerobic threshold for extended periods of time, often with an anaerobic finish. Much less so with marathons due to the increased distance involved. Food for thought? Might make an interesting study, if it isn't already out there.

Yes, but my point is that a marathon -or backpacking ect. is not a way to build up the body or train whether or not you want muscle bulk. You must train to be able to run a marathon but the marathon itself (or backpacking trip ect) is no way to stay fit. its a sport. Like how one needs to train to box, but getting a fist in the face is not "healthy".
I get quite surprised at how much muscle I lose after 2 weeks on the trail let alone fat. It didnt make me weak but made me weaker. True body builders arnt known for their strength. they train only for bulk (well,most anyhow) while much leaner people who train for conditioning and strength like -kettlebells will be a whole lot stronger.
My point is that short intense work outs will be more beneficial for both strength and conditioning and your body wont loss muscle in the process like it would if it was sustained.