What is the best approach to achieve weight loss?

How to Lose Weight

To lose weight effectively, create a caloric deficit of 500-750 kcal/day by consuming 1,200-1,500 kcal/day for women or 1,500-1,800 kcal/day for men, combined with at least 150 minutes per week of moderate-intensity physical activity. 1

The Fundamental Principle

The cornerstone of all successful weight loss is achieving an energy deficit—consuming fewer calories than your body expends. 1 This principle supersedes any specific dietary approach, as all effective diets work through this mechanism. 1, 2

Target a weight loss of 0.5-1 kg (1-2 pounds) per week during the first 6 months, aiming for 5-10% reduction of initial body weight. 1 This rate of loss produces clinically meaningful improvements in blood pressure, cholesterol, triglycerides, and glucose levels. 1

Dietary Strategies That Work

Any of the following dietary approaches will produce equivalent weight loss if the caloric deficit is maintained—the key is choosing one you can sustain long-term: 1

• Low-fat diet (≤30% of calories from fat) 1
• Low-carbohydrate diet (initially <20g/day carbohydrate, progressing as tolerated) 1
• Mediterranean-style diet with caloric restriction 1
• Higher-protein diet (25% of calories from protein) 1
• Low-glycemic-load diet 1

Practical Implementation

Reduce dietary fat intake as the most practical method to decrease total calories, since fat is the most energy-dense macronutrient at 9 calories per gram. 1 Spontaneous food consumption decreases when dietary fat is reduced. 1

Eliminate or severely restrict liquid calories including sodas, juices, and alcohol. 1 These provide calories without satiety and represent an easy target for caloric reduction.

Use portion-controlled servings or meal replacements to enhance adherence, as individuals with obesity consistently underestimate their caloric intake when self-selecting foods. 1

Physical Activity Requirements

Begin with 150 minutes per week of moderate-intensity aerobic activity (such as brisk walking), equivalent to 30 minutes on most days. 1 This supports initial weight loss and provides cardiovascular benefits independent of weight reduction. 1

Progress to 200-300 minutes per week of physical activity for long-term weight maintenance after achieving initial weight loss. 1 This higher activity level is essential to prevent weight regain. 1

Physical activity alone produces minimal weight loss (typically <2 kg), but it is critical for maintaining weight loss and improves insulin sensitivity, cardiovascular fitness, and reduces visceral fat preferentially. 1

Behavioral Modification Components

Successful weight loss requires structured behavioral support beyond diet and exercise alone: 1

• Self-monitor daily food intake, physical activity, and weight using food diaries or apps 1
• Set specific, measurable goals with incremental targets rather than attempting dramatic changes 1
• Attend at least 14 sessions with a trained interventionist over 6 months for high-intensity comprehensive lifestyle intervention 1
• Maintain monthly contact with a healthcare provider or interventionist after the initial 6 months 1

Group behavioral therapy produces average weight loss of 0.5 kg/week and 9% of initial weight over 20-26 weeks. 1 Patients typically regain 30-35% of lost weight in the year following treatment, but those maintaining regular contact with treatment providers show better long-term outcomes. 1

Critical Pitfalls to Avoid

Do not pursue very-low-calorie diets (<800 kcal/day) outside of medical supervision, as these produce rapid initial weight loss but result in weight regain when normal eating resumes and lack long-term efficacy. 1

Avoid very-low-carbohydrate diets (<130g/day) for long-term use due to unknown effects and elimination of important food sources. 1 While they may be used short-term, sustainability is poor.

Do not expect physical activity alone to produce significant weight loss—it must be combined with caloric restriction. 1 However, never skip exercise as it is essential for weight maintenance and metabolic health.

Pharmacological Adjuncts

For individuals with BMI ≥30 kg/m² or BMI ≥27 kg/m² with obesity-related comorbidities who have not achieved adequate weight loss with lifestyle modification alone, consider FDA-approved weight loss medications: 1

• Orlistat (inhibits pancreatic lipase, causing partial fat malabsorption) should be taken with each fat-containing meal, maximum 3 capsules daily, combined with a multivitamin at bedtime 3
• Phentermine (appetite suppression) for short-term use 1
• GLP-1 receptor agonists (semaglutide, liraglutide) demonstrate superior visceral fat reduction 4

Monitoring and Long-Term Maintenance

Weigh yourself at least weekly to detect early weight regain. 1 Most weight loss occurs in the first 6 months, with gradual regain of 1-2 kg/year common without continued intervention. 1

Calculate your BMI (weight in kg ÷ height in m²) and maintain it between 18.5-25.0 kg/m². 1 Measure waist circumference, targeting <88 cm (35 inches) for women and <102 cm (40 inches) for men. 1

If weight regain occurs after stopping active weight loss efforts, resume the structured dietary and exercise program that produced initial success. 3 Weight loss maintenance requires permanent lifestyle changes, not temporary dieting.