siodine comments on Minimum viable workout routine - Less Wrong

12 Post author: RomeoStevens 21 June 2012 04:19AM

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Comment author: siodine 21 June 2012 11:08:41PM * 11 points [-]

Thought this might be a good place to dump some excerptions from evernote:

Review: Energetics of Obesity and Weight Control: Does Diet Composition Matter?

Greater average weight losses (2.5 kg over 12 weeks) have been reported for low-carbohydrate diets (<90 g/day) compared with traditional low-fat (<25% of energy), hypocaloric diets, implying a 233 kcal/day greater energy deficit. It has therefore been suggested that a low-carbohydrate diet may provide a metabolic advantage (an increase in energy expenditure), resulting in a positive effect on weight loss and maintenance. However, a review of studies in which 24-hour energy expenditure was measured did not provide evidence to support a metabolic advantage of low-carbohydrate diets and showed little evidence of a metabolic advantage of high-protein (>25% of energy) diets. Nonetheless, diets high in protein, but either low or modest in carbohydrate, have resulted in greater weight losses than traditional low-fat diets. We speculate that it is the protein, and not carbohydrate, content that is important in promoting short-term weight loss and that this effect is likely due to increased satiety caused by increased dietary protein. It has been suggested that the increased satiety might help persons to be more compliant with a hypocaloric diet and achieve greater weight loss.

...energy deficits realized by a person will be smaller than the energy restriction because the three components of total energy expenditure (thermic effect of food [TEF], resting metabolic rate [RMR], and the energy expended in physical activity) decrease in response to an energy deficit and weight loss. If a person decreases energy intake, the TEF will decrease by an amount roughly equal to about 10% of the decrease in energy intake. Following energy restriction, RMR will also decrease, first as an adaptive response to the energy deficit and then as a result of smaller body size. Finally, the energy costs of physical activity will decrease for the same physical activities, also as a result of smaller body size (4). When reductions in these three components of total energy expenditure are averaged over a 12-week weight loss, they reduce the predicted energy deficits by one fourth to one third.

Still, the basic relationship between body energy stores and energy deficit shown in the Table [see pdf] suggests the greater average weight losses reported for low-carbohydrate diets are due to a 233 kcal/day greater energy deficit. What might cause this greater energy deficit? Is it due to metabolic advantage, or a difference in energy intake? ... [Exposition of studies for following conclusion -- ketogenic diet referenced]. ...Taken together, these studies provide little support for the hypothesis that a low-carbohydrate diet increases energy expenditure and, if anything, a low-carbohydrate diet may decrease energy expenditure, particularly if the carbohydrate intake is very low.

[Similar conclusion with high-protein diet followed, but results are better than low-carb.]

Combining the results of these studies, there is an effect of dietary macronutrient composition on energy expenditure, but the effect of substituting fat for carbohydrate is generally small and in the opposite direction needed to support the suggestion of a metabolic advantage. In the case of the two studies that substituted protein for carbohydrate, the effects were contradictory. Thus, these observations do not explain the 2.5 kg, or more, greater weight losses reported for low-carbohydrate diets compared with traditional low-fat diets and thus do not support the hypothesis of a metabolic advantage for low-carbohydrate diets.

If the effect of dietary macronutrient distribution on energy expenditure is minimal, what else might explain the greater weight loss observed for low-carbohydrate or high-protein diets? The likely explanation is greater dietary compliance. Thus, on a theoretical basis, low-carbohydrate diets with a high protein content are producing the expected weight loss, whereas low-fat diets are not. Given the minimal effect of macronutrient composition on energy expenditure, the most likely explanation of the greater weight loss is that participants complied with the energy prescription of the low-carbohydrate/high-protein diet, but not the low-fat diet. In support of this, it has been reported that protein has a higher satiating effect than carbohydrate; thus, a high-protein diet may help participants comply with energy restriction.

A second factor that can contribute to improved compliance is the limitation of food choices associated with low-carbohydrate diets. Many foods are not permitted in low-carbohydrate diets because they contain too much carbohydrate.

In addition to improved compliance, low-carbohydrate diets are also known to induce small losses of body water that can contribute to weight loss.The loss of liver and muscle glycogen secondary to carbohydrate intakes below that required to sustain glycogen stores results in water loss of 1.9 kg in the first 10 days of a very–low carbohydrate diet (12). This contributes to the early rapid weight loss often reported by participants consuming low-carbohydrate diets. Aside from the weight itself, this water loss may also help participants comply with their diets during the early phase of the diet, because modest increases in carbohydrate intake will result in the return of the glycogen stores and associated water. The water will result in a small rapid weight gain that may serve as negative feedback and help direct the participant back to compliance.

Comment author: siodine 21 June 2012 11:08:52PM * 10 points [-]

Review: Diet in the management of weight loss.

Low-calorie diets can lower total body weight by an average of 8% in the short term. These diets are well-tolerated and characterize successful strategies in maintaining significant weight loss over a 5-year period. Very-low-calorie diets produce a more rapid weight loss but should only be used for fewer than 16 weeks because of clinical adverse effects. Diets that are severely restricted in carbohydrates (3%–10% of total energy intake) and do not emphasize a reduction of energy intake may be effective in reducing weight in the short term, but there is no evidence that they are sustainable or innocuous in the long term because their high saturated-fat content may be atherogenic. Fat restriction in a weight-loss regimen is beneficial, but the optimal percentage has yet to be determined.

Which diets result in safe weight loss, have positive long-term consequences for chronic disease risk factors, and are sustainable in the long term? This question has been only partially answered. Comparing dietary trials is difficult for several reasons: diet compositions vary in the amount and type of carbohydrates and fats, amount of protein, and degree that energy intake is restricted, all of which have intricate bearings on weight regulation; diets have specific actions on appetite and food preference that affect drop-out rates; study populations may have different associated diseases that modify outcomes; and the choice of statistical analyses can bias results.

The National Institutes of Health reviewed 34 randomized controlled trials to assess the effectiveness of low-calorie diets for lowering body weight, decreasing abdominal fat and improving cardiorespiratory fitness.8 The review concluded that low-calorie diets can lower total body weight by an average of about 8% during a period of 3–12 months (evidence category A). Weight-loss and weight-loss maintenance interventions lasting 3–4.5 years (4 studies only) resulted in an average weight loss of 4%, well below the definition proposed for successful weight loss (a decrease in 10% of body weight sustained for more than 1 year).7 Low-calorie diets resulting in weight loss also lower the amount of abdominal fat, as shown by a reduction in waist circumference of 1.5–9.5 cm (evidence category A). The National Institutes of Health review also concluded that low-calorie diets alone do not improve cardiorespiratory fitness as measured by maximum rate of oxygen consumption (evidence category B),8 which reinforces the importance of combining diet and exercise programs in weight-loss interventions. Behaviour therapy in conjunction with dietary interventions (including low-calorie diets) has been shown to result in additional weight loss in the short term (1 year) but not in the long term (3–5 years) (evidence category B).

There is a debate regarding the effectiveness of low-fat diets in weight reduction.23–28 Astrup and colleagues26 conducted a meta-analysis of 16 trials of 2–12 months' duration, of which 14 were randomized. They reported that low-fat diets without intentional restriction of energy intake resulted in greater weight loss (3.2 kg, 95% confidence interval 1.9–4.5 kg, p < 0.001) than did habitual, or medium-fat, diets ad libitum. ... The National Institutes of Health review also concluded that lower-fat diets (20%–30% of total energy intake) contribute to lower energy intake; there is little evidence that low-fat diets with no reduction in energy intake result in weight loss.

We still have no definitive answer as to which diets sustain long-term weight loss. The National Weight Control Registry in the United States provides useful information regarding successful weight-loss maintenance strategies.81 This registry includes people who have lost more than 13 kg of body weight and successfully maintained that weight loss for over 5 years. Over 4000 people are in the registry. The dietary pattern generally shared among participants included low amounts of fat (about 24% of the total daily energy intake), high amounts of carbohydrate, and a low energy intake (5460–6300 kJ/d). Most eat breakfast daily, self-monitor weight and are physically active. Other studies report similar strategies for successful weight-loss maintenance, such as monitoring food portion sizes, energy and fat intake, and body weight, and avoiding the use of food to regulate mood.

Overall, low-calorie diets are a safe strategy for weight loss. A sample 5040-kJ diet plan based on Canada's Food Guide to Healthy Eating is outlined in the online appendix (available at www.cmaj.ca/cgi/content/full/174/1/56/DC1). A sedentary woman 45 years of age with a body mass index of 31 kg/m2 (height 167.6 cm [5'6"], weight 87.5 kg [192.5 pounds]) and an energy requirement of 7988 kJ per day (calculated using the Harris–Benedict equation) can achieve a body mass index of about 26 kg/m2 after 6 months on a 5040-kJ/d low-calorie diet. ... Low-carbohydrate diets and diets high in saturated fat are not recommended.

Successful Weight Loss Among Obese U.S. Adults

Purpose: To identify strategies associated with losing at least 5% and 10% of body weight.

Sciamanna and colleagues identifıed 14 strategies reported to be successful for 10% weight loss among a national mail panel survey, reporting the strongest associations for weight loss programs, eating fruits and vegetables, eating healthy snacks, limiting carbohydrates, controlling portions, doing different kinds of exercises, and focusing on the progress they had made. Among members of the National Weight Control Registry, the most common strategies associated with success included restricting types of foods, limiting quantity of food, and counting calories.

Results: Of 4021 obese adults, 2523 (63%) reported trying to lose weight in the previous year. Among those attempting weight loss, 1026 (40%) lost ?5% and 510 (20%)lost ?10% weight. After adjustment for potential confounders, strategies associated with losing 5% weight included eating less fat ; exercising more; and using prescription weight loss medications. Eating less fat; exercising more; and using prescription weight loss medications were also associated with losing 10% weight, as was joining commercial weight loss programs. Adults eating diet products were less likely to achieve 10% weight loss. Liquid diets, nonprescription diet pills, and popular diets had no association with successful weight loss.

The present study has several limitations. Because this is a cross-sectional observational study based mostly on self-reported information, results suggest associations and do not signify causality.Although there is likely reporting bias for body weight,this study demonstrates a high correlation between self-reported current body weight and measured body weight.

Energetics of obesity and weight control: does diet composition matter?

Diet in the management of weight loss

Successful Weight Loss Among Obese U.S. Adults