From the Guidelines
Calorie restriction is currently the most recommended method for weight loss, as it has been consistently shown to be effective in achieving a modest weight loss of approximately 0.5 kg/week. The 2023 study published in Obesity Reviews 1 provides a comprehensive overview of dietary interventions for weight loss, including calorie restriction, low-calorie diets, and very low-calorie diets. According to this study, a hypocaloric balanced diet with a daily energy intake goal of 1200-1500 kcal/day for women and 1500-1800 kcal/day for men can achieve modest weight loss.
Key Considerations
- The choice of calorie-restricted diet can be individualized to the patient's preferences and health status, as recommended by the 2014 AHA/ACC/TOS guideline for the management of overweight and obesity in adults 1.
- Very-low-calorie diets (<800 kcal/day) should be used only in limited circumstances in a medical care setting where medical supervision and a high-intensity lifestyle intervention can be provided.
- Intermittent fasting may offer additional benefits beyond weight loss, including improved insulin sensitivity and cellular repair processes called autophagy, but its superiority over calorie restriction for weight loss is not clearly established.
Important Factors
- The most important factor for sustainable weight loss is finding an approach that fits your lifestyle and that you can maintain long-term.
- Pregnant women, those with diabetes, eating disorders, or certain medical conditions should consult healthcare providers before trying any weight loss method.
- During eating windows, focus on nutrient-dense foods rather than processed options to ensure adequate nutrition and support overall health.
From the Research
Comparison of Intermittent Fasting and Calorie Restriction for Weight Loss
- Both intermittent fasting (IF) and calorie restriction (CR) are effective strategies for weight loss, with studies showing significant reductions in body weight and fat mass 2, 3, 4.
- IF involves caloric restriction for one or several days a week, or every day as the prolongation of the overnight fast, while CR involves reducing daily caloric intake by 15-60% of usual caloric intake every day 2, 3.
- Research suggests that IF may be more effective for the retention of lean mass compared to CR, with one study finding that less fat-free mass was lost in response to IF versus CR 3.
- A systematic review and meta-analysis found that IF led to slightly greater short-term reductions in body weight and fat mass compared to CR, although these differences are not clinically significant 4.
- Both IF and CR have similar effects on lean mass, waist and hip circumference, blood pressure, lipid profiles, and glucose metabolism, although IF may improve insulin sensitivity 4.
Limitations and Future Research
- The current scientific evidence is limited by the sample size and duration of the studies, making it difficult to prescribe IF or CR as reliable, routine methods for successful and stable weight loss 2, 5.
- More research is needed to explore the long-term clinical relevance of IF in obese populations, as well as to determine the optimal diet strategy for weight loss and maintenance 6, 4.
- Individualized approaches to weight loss and maintenance may be necessary, taking into account patient preferences and needs 6.