Is intermittent fasting a safe way to lose weight if you have diabetes?

Shamera Robinson, MPH, RDN responds

Even if you haven’t heard about intermittent fasting, the idea of fasting—going without food, or both food and drink, for a period of time—probably sounds familiar. People fast for reasons ranging from upcoming medical tests and procedures to religious and spiritual practice. However, the conversation around fasting as a strategy for weight loss is becoming more popular among health professionals.

What To Know

Intermittent fasting is a way of eating that focuses more on when you eat than what you eat. One popular interpretation, known as the 16:8 method, involves fasting for 16 hours and eating meals within an eight-hour window. With the 16:8 plan, you could have dinner at 7 p.m., skip breakfast the next morning, and eat lunch at 11 a.m.

Another approach: Set eating and fasting times for the week. You might follow your regular eating routine for five days of the week, for instance, but then drastically reduce your calories for the remaining two days. Fasting can also include completely restricting food for a full 24 hours, allowing only drinks such as water, unsweetened tea, and black coffee.Fasting can sound extreme until you consider that many of us fast without even realizing it. Did you get eight hours of sleep last night? That means you fasted for at least eight hours. (That’s where we get “breakfast.” You’re breaking your overnight fast.) Intermittent fasting can be done in many different ways, and your provider will work with you to determine if this is a safe and suitable option based on your individual needs.

Find Out More

The research on intermittent fasting is limited. But small, short-term studies have shown that it may help some people lose weight. Limiting the amount of food you eat and/or the length of time you allow yourself to eat can greatly reduce the total number of calories you consume. This type of calorie restriction often leads to weight loss, which may seem like a worthy benefit, considering it can help improve diabetes management.

But it’s not so simple. Restricting the foods that provide your body with nutrients may lead to headaches and low energy, making fasting difficult to sustain. And, more important, weight-loss benefits may be outweighed by hypoglycemia risks for those taking insulin, sulfonylureas, or meglitinides. Going too long without eating can cause blood glucose to drop. Limiting food could also lead to overly restrictive habits during fasting hours or binge eating during feasting hours, which makes it hard to maintain stable blood glucose levels. Disordered eating, not uncommon for people with diabetes, may mean fasting is inadvisable.

Takeaway

There isn’t enough research to support intermittent fasting as a safe long-term practice for people with diabetes. If you decide to try it, work with your health care provider to form a safe and sustainable strategy. You’ll likely need to change your medication plan if you take insulin, sulfonylureas, or meglitinides, for instance. And you’ll need to stay hydrated with water to protect your kidneys. Ultimately, the ideal strategy for weight loss is one that’s medically safe, complements your lifestyle, and is easy to follow.

Shamera Robinson, MPH, RDN, is a registered dietitian nutritionist and associate director of nutrition for the American Diabetes Association.