Weight Loss Is Determined By Calories In Vs. Calories Out
Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates.
Sacks FM, Bray GA, Carey VJ, Smith SR, Ryan DH, Anton SD, McManus K, Champagne CM, Bishop LM, Laranjo N, Leboff MS, Rood JC, de Jonge L, Greenway FL, Loria CM, Obarzanek E, Williamson DA.
Department of Nutrition, Harvard School of Public Health, Boston, USA.
Abstract
BACKGROUND:
The possible advantage for weight loss of a diet that emphasizes protein, fat, or carbohydrates has not been established, and there are few studies that extend beyond 1 year.
METHODS:
We randomly assigned 811 overweight adults to one of four diets; the targeted percentages of energy derived from fat, protein, and carbohydrates in the four diets were 20, 15, and 65%; 20, 25, and 55%; 40, 15, and 45%; and 40, 25, and 35%. The diets consisted of similar foods and met guidelines for cardiovascular health. The participants were offered group and individual instructional sessions for 2 years. The primary outcome was the change in body weight after 2 years in two-by-two factorial comparisons of low fat versus high fat and average protein versus high protein and in the comparison of highest and lowest carbohydrate content.
RESULTS:
At 6 months, participants assigned to each diet had lost an average of 6 kg, which represented 7% of their initial weight; they began to regain weight after 12 months. By 2 years, weight loss remained similar in those who were assigned to a diet with 15% protein and those assigned to a diet with 25% protein (3.0 and 3.6 kg, respectively); in those assigned to a diet with 20% fat and those assigned to a diet with 40% fat (3.3 kg for both groups); and in those assigned to a diet with 65% carbohydrates and those assigned to a diet with 35% carbohydrates (2.9 and 3.4 kg, respectively) (P>0.20 for all comparisons). Among the 80% of participants who completed the trial, the average weight loss was 4 kg; 14 to 15% of the participants had a reduction of at least 10% of their initial body weight. Satiety, hunger, satisfaction with the diet, and attendance at group sessions were similar for all diets; attendance was strongly associated with weight loss (0.2 kg per session attended). The diets improved lipid-related risk factors and fasting insulin levels.
CONCLUSIONS:
Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize. (ClinicalTrials.gov number, NCT00072995.)
2009 Massachusetts Medical Society
You: That’s great, but will you explain it to me like I’m five?
Me: Absolutely.
The best diet for weight loss is still intensely debated and there has been very few well conducted studies which looked at this issue. Is a high protein diet better, or high carb or a high fat diet better?
What were the strengths of the weight loss study?
A recent study looked at this very issue and received a lot of good attention.
- Large number of participants: There were 811 participants from diverse backgrounds irrespective of age, income, geography and included a large percentage of men. Obviously the largest RCT related to weight loss diets.
- High rate of retention: The people who dropped out of the study were low which was a serious problem in other weight loss studies.
- Long Duration: The diet lasted for 2 years which is the longest trial for randomized weight loss trial.
- Compliance accessed: Compliance was assessed by objective markers .For example, urinary nitrogen excretion was used to asses adherence to the protein intake.
- Intense Treatment: Treatment included individual and group instructional sessions to promote adherence.
What was the design of the study?
Eight hundred and eleven participants were randomly assigned to four different diets:
- 20% fat, 15% protein, and 65% carbs; Low fat, Average protein
- 20% fat, 25% protein, and 55% carbs; Low fat, High protein
- 40% fat, 15% protein, and 45% carbs; High fat, Average protein
- 40% fat, 25% protein, and 35% carbs; High fat, High protein
All of the diets had an average calorie deficit of 750 calories from the patients’ aggregate baseline caloric intake. Participants followed the diets for two years, during which time they were also expected to engage in 90 minutes of moderate exercise each week, keep a daily food diary, fill out a Web-based tool that monitored how closely their intake adhered to their assigned diet, and attend group and individual sessions to promote adherence
What were the results of the study?
All the diets were equally successful in promoting moderate weight loss and maintaining this loss for over 2 years. Weight loss averaged 3-4 years after 2 years.
Practical Recommendations
Source
- Any diet which emphasizes calorie restriction will work and the specific amount of protein, fat or carbs of the diet does not matter.
- Diets should be tailored to the person based on their individual and cultural preferences than based on nutritional recommendations for long term success.
- Behavioral strategies maybe more important in weight loss diets than their composition.
Calories are king.
The most important factors for weight loss are calories in vs. calories out and your ability to stick to a plan. A diet composed of moderation, in my mind, will always reign supreme due to the participants ability to still enjoy foods that they love.
