From the Guidelines
Rapid weight changes from intermittent fasting can be dangerous and should be approached with caution, particularly for individuals with pre-existing medical conditions like diabetes, where the risk of hypoglycemia and other complications is heightened, as noted in the 2025 standards of care in diabetes 1. When considering intermittent fasting, it's crucial to understand the potential risks, including muscle loss, nutritional deficiencies, metabolic slowdown, gallstone formation, dehydration, and increased stress on the body.
- Key considerations for safe intermittent fasting include:
- Gradual weight loss of 1-2 pounds per week to minimize metabolic slowdown and other risks
- Staying well-hydrated to prevent dehydration and support overall health
- Consuming nutrient-dense foods during eating windows to prevent nutritional deficiencies
- Including adequate protein in the diet to preserve muscle mass For individuals with diabetes, managing medications during fasting is critical, as outlined in the 2025 standards of care in diabetes 1, which provides guidance on adjusting the timing and dose of medications like metformin, sulfonylureas, and insulin to prevent hypoglycemia and other complications.
- Medication adjustments may include:
- Taking medications like metformin and new generation sulfonylureas at main mealtime to minimize the risk of hypoglycemia
- Reducing the dose of insulin for meals followed by fasting by 35-50% to prevent hypoglycemia
- Choosing insulins with a lower risk of hypoglycemia and adjusting the dose based on individual needs and glucose levels, as recommended in the 2025 standards of care in diabetes 1.
From the Research
Dangers of Rapid Weight Changes with Intermittent Fasting
- Rapid weight changes can be a concern with intermittent fasting, as it can lead to nutrient deficiencies and other health problems 2, 3
- Some studies have shown that intermittent fasting can be an effective way to lose weight and improve metabolic health, but more research is needed to fully understand its effects 4, 5
- Certain populations, such as those with Type 2 diabetes, may be at increased risk of hypoglycemia when using intermittent fasting 6
- The safety and feasibility of intermittent fasting compared to calorie restriction has not been well-studied, and more research is needed to determine its long-term effects 2
Potential Risks of Intermittent Fasting
- Hypoglycemia: intermittent fasting can increase the risk of hypoglycemia, particularly in individuals with Type 2 diabetes 6
- Nutrient deficiencies: rapid weight changes can lead to nutrient deficiencies if the diet is not well-planned 3
- Other health problems: intermittent fasting can also lead to other health problems, such as dehydration and electrolyte imbalances, if not done properly 2
Importance of Further Research
- More research is needed to fully understand the effects of intermittent fasting on human health, particularly in the long-term 2, 3, 5
- Studies should investigate the safety and feasibility of intermittent fasting compared to calorie restriction, as well as its effects on different populations, such as older adults and those with chronic diseases 2, 5