Frequently Asked Questions
What do the amounts of fat, protein, and carbohydrates have to do with weight loss?
Sacks et al. conducted a randomized clinical trial among 811 overweight adults enrolled in 2-year study Subject were randomly assigned to one of 4 diets:
- 20% fat, 15% protein, 65% carbohydrates (low-fat, average-protein)
- 20% fat, 25% protein, 55% carbohydrates (low-fat, high protein)
- 40% fat, 15% protein, 45% carbohydrates (high-fat, average-protein)
- 40% fat, 25% protein, 35% carbohydrates (high-fat, high-protein)
The authors summarized the results as follows:
"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."
"Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize."
What are the recommendation for children and adolescents?
Almost 20% of adolescents in the US are obese, and it is important to be able to advise them regarding dieting strategies that are safe and effective. Adolescents are particularly vulnerable to the advertising and false promises of popular diets. It is important to assess what and how your pediatric patients are eating, and encourage them to eat a wide variety of foods. Crash dieting, avoiding certain food groups, and disordered eating are particularly common among overweight, competitive athletes, and many young women. Nevertheless, small studies have shown that low-carbohydrate diets and energy-restricted low-fat diets have similar short-term weight management successes, and they are generally safe. However, there is very limited data on the long-term outcomes and safety of specific diets for children and adolescents. In adolescents, emphasis should be put on the following lifestyle changes that have been shown to be most effective:
- Focus on food quality rather than fat restriction
- Encourage good sleep hygiene
- Promote stress reduction
- Decrease sedentary behaviors such as TV and computer use
For more information, consult the following resources:
- Agency for Healthcare Research and Quality: Pediatric Weight management evidence-based nutrition practice guidelines: http://guidelines.gov/content.aspx?id=12821
- New Safety Data on the High-Protein-Low-Carbohydrate Diet in AdolescentsThe Journal of Pediatrics, Volume 157, Issue 2, Pages 184-185 Miriam Vos
- Weight Loss Strategies for Adolescents: http://jama.jamanetwork.com.ezproxy.bu.edu/article.aspx?articleid=1104944#DIET
How successful are these diets?
Reduced-calorie diets resulted in clinically meaningful weight loss regardless of which macronutrients they emphasized:
- Average weight loss of 6 kilograms (13.2 lbs.) at 6 months
- Average weight loss of 2.9 - 3.6 kilograms (6.4 - 7.9 lbs.) at 2 years
Main Caveat: The mean reported intakes at 6 months and 2 years did NOT reach target levels for macronutrients
What are the keys to successful weight loss?
American Heart Association - No-Fad Diet tips: http://www.heart.org/HEARTORG/GettingHealthy/WeightManagement/No-Fad-Diet-Tips_UCM_305838_Article.jsp
The National Weight Control Registry (NWCR) over 5,000 registrants (80% women) who have provided information suggesting that those persons who are able to lose weight and keep it off consume low fat diets, reduce the number of calories consumed, and expend on average 400 kcal of physical activity on a daily basis.
Observations from the NWCR:
- Registrants have lost an average of 66 lbs. (range 30-300) and kept it off for 5.5 years.
- Some have lost the weight rapidly, while others have lost weight very slowly - over as many as 14 years.
- 45% of registry participants lost the weight on their own; the other 55% lost weight with the help of some type of program.
- 98% of Registry participants report that they modified their food intake in some way to lose weight.
- 94% increased their physical activity, with the most frequently reported form of activity being walking.
- Most report continuing to maintain a low calorie, low fat diet and doing high levels of activity.
- 78% eat breakfast every day.
- 75% weigh themselves at least once a week.
- 62% watch less than 10 hours of TV per week.
- 90% exercise, on average, about 1 hour per day.
Cardinal Behaviors of Successful Long-term Weight Management
- Self-monitoring: record food intake daily, and record body weight once a week
- Low-calorie, low-fat diet
- Total energy intake: 1300 -1400 kcal/day
- Energy intake from fat: 20-25%
- Eat breakfast daily
- Regular physical activity: 2500-3000 kcal/wk (e.g., walk 4 miles/day)
What is the best "healthy eating" pattern?
There are many variations on a successful program, but a successful program will likely have the following characteristics:
- It should include foods from all 5 food groups and include the correct number of servings from each.
- It should include foods you will enjoy eating for the rest of your life.
- It should include foods you can buy at the supermarket.
- It should include your favorite foods.
- It should fit fit your budget and lifestyle.
- It should be combined with regular physical activity.
What are the Criteria for Selecting a Weight Loss Program?
- It encourages physical activity, behavioral principles, and balanced nutrition. Be wary of diets that eliminate entire food groups.
- Target is for weight loss of 1-2 lbs/week
- A qualified staff
- Risk of using products/service
- Reasonable cost of program
- Long-term weight maintenance component
- Addresses relapse control and plateaus
- Evidence of successful outcomes
- Federal Trade Commission Resource: Partnership for Healthy Weight Management