From the Guidelines
Rapid weight changes due to restrictive diets can be dangerous and are not recommended for sustainable weight management, with the most recent and highest quality study suggesting a balanced approach with moderate calorie restriction of 1200-1500 kcal/day for women and 1500-1800 kcal/day for men 1. These dangers include muscle loss, nutritional deficiencies, metabolic slowdown, gallstones, and psychological impacts like disordered eating patterns. When the body experiences severe caloric restriction, it often breaks down muscle tissue for energy, leading to weakness and a lower metabolic rate. Some key points to consider when evaluating the risks of rapid weight changes due to restrictive diets include:
- Nutritionally, restrictive diets typically lack essential vitamins, minerals, and macronutrients needed for proper bodily function.
- The body also responds to severe restriction by slowing metabolism as a survival mechanism, making weight maintenance harder long-term.
- Rapid weight loss increases the risk of gallstone formation due to changes in bile composition.
- Psychologically, the cycle of restriction often leads to binge eating and an unhealthy relationship with food. Instead of restrictive dieting, aim for gradual weight changes of 1-2 pounds per week through balanced nutrition and regular physical activity, as recommended by the 2023 consensus on care and management of obesity 1. This approach allows the body to adapt properly while maintaining muscle mass and metabolic health, and is more likely to result in sustainable weight management. It is also important to note that very-low-calorie diets (<800 kcal/d) should be used only in limited circumstances in a medical care setting where medical supervision and a high-intensity lifestyle intervention can be provided, as stated in the 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults 1.
From the Research
Dangers of Rapid Weight Changes due to Restriction Diet
- Rapid weight changes due to restriction diets can have various effects on individuals, particularly those with binge eating disorder or obesity.
- A study published in 2015 2 found that severe dietary energy restriction can be beneficial for overweight or obese individuals with pre-treatment binge eating disorder, and does not necessarily trigger binge eating in those without binge eating disorder.
- However, another study from 2005 3 suggested that the addition of orlistat to cognitive behavioral therapy guided self-help (CBTgsh) was associated with greater weight loss than the addition of placebo to CBTgsh, but also noted that significant and comparable improvements in eating disorder psychopathology and psychological distress occurred in both treatments.
Comparison of Dietary Restriction Methods
- A 2011 study 4 compared the effects of daily calorie restriction (CR) versus intermittent CR on weight loss, fat mass loss, and lean mass retention in overweight and obese adults, and found that both diets are equally effective in decreasing body weight and fat mass.
- However, the study also found that less fat-free mass was lost in response to intermittent CR versus daily CR, suggesting that intermittent CR may be more effective for the retention of lean mass.
- A more recent review from 2021 5 examined the effects of restrictive and non-restrictive dietary weight loss interventions on neurobehavioral factors related to body weight control, and found that restrictive diets may improve eating behaviors and lead to short-term changes in brain structure and improvements in cerebrovascular markers.
Predicting Response to Treatment
- A 2007 study 6 examined the concept of rapid response in obese patients with binge eating disorder, and found that rapid response, defined as 70% or greater reduction in binge eating by the fourth treatment week, was a significant predictor of outcomes, including binge eating remission and 5% weight loss.
- The study suggested that rapid response may be an important factor to consider in treatment planning, as it may inform the decision to continue or modify treatment approaches.