What is the most effective dietary approach for achieving weight loss?

From the Guidelines

The best diet for weight loss is one that creates a calorie deficit of 500-1000 kcal/d, with a focus on whole foods, including vegetables, fruits, lean proteins, whole grains, and healthy fats, while limiting processed foods, added sugars, and refined carbohydrates, as recommended by the 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults 1. To achieve this, it's essential to match intake of total energy to overall energy needs, and achieve a level of physical activity that matches or exceeds energy intake, as stated in the AHA dietary guidelines: revision 2000 1. The key is to find a sustainable eating pattern that can be maintained long-term, rather than following a specific diet trend. Some of the most effective dietary approaches for weight loss include:

• A diet from the European Association for the Study of Diabetes Guidelines
• Higher-protein diet
• Higher-protein Zone-type diet
• Lacto–ovo–vegetarian–style diet with prescribed energy restriction
• Low-calorie diet with prescribed energy restriction
• Low-carbohydrate diet
• Low-fat vegan-style diet
• Low-fat diet
• Low–glycemic–load diet
• Lower-fat, high-dairy diets
• Macronutrient-targeted diets
• Mediterranean-style diet
• Moderate-protein diet as outlined in the 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults 1. Aim for a moderate calorie reduction of 500-750 calories per day, which typically leads to 1-2 pounds of weight loss per week, and prioritize regular protein intake (about 0.7-1 gram per pound of body weight) to preserve muscle mass during weight loss, as recommended by the 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults 1. Remember to stay hydrated by drinking plenty of water, which can also help control hunger. Consistency matters more than perfection, and finding a sustainable eating pattern that can be maintained long-term is more important than following any specific diet trend. It's also important to note that weight loss requires creating an energy deficit through caloric restriction, physical activity, or both, and an energy deficit of ≥500 kcal/d typically may be achieved with dietary intake of 1200–1500 kcal/d for women and 1500–1800 kcal/d for men, as stated in the 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults 1.

From the FDA Drug Label

Use for weight loss in overweight adults, 18 years and older, when used along with a reduced-calorie and low-fat diet diet and exercise are the starting points for any weight loss program. ... use with a reduced-calorie, low-fat diet and exercise program until you reach your weight loss goal The best diet for weight loss is a reduced-calorie and low-fat diet 2 2.

• This diet should be used along with exercise 2.
• It is essential to continue with the diet and exercise program even after stopping the medication to maintain weight loss 2.

From the Research

Dietary Approaches for Weight Loss

• Various dietary approaches have been recommended for weight loss, including low-fat diets, low-carbohydrate diets, high-protein diets, and the Mediterranean diet 3
• The optimal diet for weight loss should be safe, efficacious, healthy, and nutritionally adequate, as well as culturally acceptable and economically affordable 3
• A low-calorie diet with a low fat or carbohydrate content has been recommended for weight loss, although the potential risks and long-term effectiveness of some diets remain unknown 4

Individualized Diet Strategies

• There is no single best strategy for weight management, and diet strategies should be individualized based on patient preferences and needs 4
• Healthcare providers should choose the best strategy based on patient preferences, and setting realistic goals for weight loss is key to facilitating weight loss in obese patients 3
• A combination of properly selected diet and physical activity is considered the most effective therapy for weight management 5

Specific Diets and Their Effects

• The Mediterranean diet may improve muscle endurance and power, as well as anaerobic performance in athletes, and is associated with enhanced strength performance 6
• A very-low-calorie diet may be required for a short period in some cases, although the potential risks and long-term effectiveness remain unknown 4
• The ketogenic diet or high-protein diet could be considered in some cases, although the potential risks and long-term effectiveness remain unknown 4

Importance of Physical Activity

• Physical activity is one of the main tools in the treatment of obesity, and a combination of properly selected diet and physical activity is considered the most effective therapy 5
• Physical activity has a broad effect on weight loss, including increasing energy expenditure, and its impact on aspects such as body composition, food intake, sleep, alcohol use, and mental state should be understood 5
• Older adults with grade II or III obesity who performed physical activity and those treated with liraglutide were more likely to have lost at least 5% of their body weight at 12-16 weeks 7