Medical Are all calories equivalent for fat loss?

[bohm2]

Which position offers stronger evidence? Please vote: No or Yes.

Here are a few papers taking each position:

1. No, all calories are not created equally:
Evidence:

a. Under Free-living conditions:

The results of our study challenge the notion that a calorie is a calorie from a metabolic perspective. During isocaloric feeding following weight loss, REE was 67 kcal/d higher with the very low-carbohydrate diet compared with the low-fat diet. TEE differed by approximately 300 kcal/d between these 2 diets, an effect corresponding with the amount of energy typically expended in 1 hour of moderate-intensity physical activity.

Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance
http://jama.jamanetwork.com/article...icleid=1199154

b. Under metabolic ward (hospitalization) conditions:

In comparative studies, obese patients given a low-carbohydrate (4.14 MJ [1000 kcal]) formula diet (diet Ia) lost 14.0 +/- 1.4 kg and those given an iso-energetic high-carbohydrate diet (diet Ib) 9.8 +/- 0.9 kg. The degree of weight loss was significantly different. Daily weight losses were 362 g and 298 g respectively…there was a greater mean weight loss with the low-carbohydrate diet (351 g/day) compared with that under the high-carbohydrate diet (296 g/day).

Dietetic treatment of obesity with low and high-carbohydrate diets: comparative studies and clinical results.
https://docs.google.com/file/d/0B05o7uyVl6paelpIZXdnMnNrRmM/edit?pli=1

c. Theory

Reduced thermodynamic efficiency will result in increased weight loss. The laws of thermodynamics are silent on the existence of variable thermodynamic efficiency in metabolic processes. Therefore such variability is permitted and can be related to differences in weight lost. The existence of variable efficiency and metabolic advantage is therefore an empiric question rather than a theoretical one, confirmed by many experimental isocaloric studies, pending a properly performed meta-analysis. Mechanisms are as yet unknown, but plausible mechanisms at the metabolic level are proposed.

Thermodynamics of weight loss diets
http://www.nutritionandmetabolism.com/content/pdf/1743-7075-1-15.pdf

d. Timing of food/calories

The time-restricted mice on a high-fat diet were protected from the adverse effects of a high-fat diet and showed improvements in their metabolic and physiological rhythms. They gained less weight and suffered less liver damage. The mice also had lower levels of inflammation, among other benefits.

Time-Restricted Feeding without Reducing Caloric Intake Prevents Metabolic Diseases in Mice Fed a High-Fat Diet
http://www.ncbi.nlm.nih.gov/pubmed?...etabolic Diseases in Mice Fed a High-Fat Diet

When it comes to weight gain, when you eat might be at least as important as what you eat. That's the conclusion of a study reported in the Cell Press journal Cell Metabolism published early online on May 17th.

http://www.sciencedaily.com/releases/2012/05/120517132057.htm

2. Yes, all calories are treated the same.
Evidence:

a. Under Free-living conditions:

Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize.

Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates
http://www.nejm.org/doi/pdf/10.1056/NEJMoa0804748

b. Under metabolic ward (hospitalization) conditions:

Almost all metabolic ward studies show no significant difference in weight/fat when altering macronutrient ratios if calories are the same. And with respect to the Rabast study it has been criticized because:

Rabast and company did not measure body composition among their subjects. So we don’t know whether the lost weight came from water, lean tissue, or fat. But some of their other data indicates that the extra losses came from lean tissue, glycogen and/or water. In their 1981 study, Rabast et al observed significantly greater potassium excretion on the low-carbohydrate diets during weeks one and two. A considerable amount of the potassium inside our bodies is bound up with glycogen, so the greater potassium losses in Rabast's low-carbohydrate dieters may indeed be a reflection of greater glycogen, and hence water losses.

Loss of weight, sodium and water in obese persons consuming a high- or low-carbohydrate diet.
http://www.colorado.edu/intphys/Class/IPHY3700_Greene/pdfs/discussionEssay/weightLossStudies/rabast.pdf

Because considerable potassium is bound up with hydrated glycogen (0.45 mmol K/g glycogen), the loss will result of > 200 mmol K.

Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition.
http://www.ajcn.org/content/56/1/292S.full.pdf

c. Theory

In addition, we concede that the substitution of one macronutrient for another has been shown in some studies to have a statistically significant effect on the expenditure half of the energy balance equation. This has been observed most often for high-protein diets. Evidence indicates, however, that the difference in energy expenditure is small and can potentially account for less than one-third of the differences in weight loss that have been reported between high-protein or low-carbohydrate diets and high carbohydrate or low-fat diets. As such, a calorie is a calorie.

Is a calorie a calorie?
http://www.ajcn.org/content/79/5/899S.full.pdf

d. Timing of food/calories

Increased meal frequency does not appear to significantly enhance diet induced thermogenesis, total energy expenditure or resting metabolic rate.

International Society of Sports Nutrition position stand: meal frequency
http://www.jissn.com/content/pdf/1550-2783-8-4.pdf

We conclude that increasing meal frequency does not promote greater body weight loss under the conditions described in the present study.

Increased meal frequency does not promote greater weight loss in subjects who were prescribed an 8-week equi-energetic energy-restricted diet.
http://www.ncbi.nlm.nih.gov/pubmed/19943985

 

[bohm2]

This is a recent study that is pretty interesting and suggests (as some have argued) that you can't out-train a bad diet and that people mistakingly put too much emphasis on exercise/physical activity for keeping slim/maximizing fat loss instead of watching what and particularly how much they eat:

These findings upend the long-held assumption that our hunter-gatherer ancestors expended more energy than modern populations, and challenge the view that obesity in Western populations results from decreased energy expenditure. Instead, the similarity in daily energy expenditure across a broad range of lifestyles suggests that habitual metabolic rates are relatively constant among human populations. This in turn supports the view that the current rise in obesity is due to increased food consumption, not decreased energy expenditure.

Hunter-Gatherers, Westerners Use Same Amount of Energy, Contrary to Theory
http://www.sciencedaily.com/releases/2012/07/120725200304.htm

Hunter-Gatherer Energetics and Human Obesity
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0040503

 

[bohm2]

I sort of changed my mind on this topic, at least slightly after reading these 2 reviews on the topic. And it seems bodybuilders were right after all, as protein does seem to offer a small metabolic advantage:

In conclusion, appetite suppression and fat oxidation were higher on a high-protein diet without than with carbohydrates exchanged for fat. Energy expenditure was not affected by the carbohydrate content of a high-protein diet.

Presence or absence of carbohydrates and the proportion of fat in a high-protein diet affect appetite suppression but not energy expenditure in normal-weight human subjects fed in energy balance.
http://www.ncbi.nlm.nih.gov/pubmed/20565999

The study is summarized nicely in this write-up by James Krieger:

The bottom line is that there is no metabolic advantage to a low carbohydrate intake that is independent of a high protein intake. There is a metabolic advantage to a high protein diet, which will increase the calories you burn by 80-100 calories per day. There is also a dramatic satiety advantage to a high protein intake. A low carbohydrate intake (low enough to cause ketosis) can increase this satiety advantage, but individual responses will vary. The best dietary approach for you will depend upon a variety of factors.

Increasing Protein, or Decreasing Carbohydrate…Which Gives You a Metabolic Advantage?
http://weightology.net/weightologyweekly/?page_id=285