With diabetes, eating makes blood sugar go up, which is generally bad. So could you try not eating at all? Research shows that you can for a while. It’s called fasting. How do you do it, how can it help, and what can go wrong?
Since bodies store extra fuel in the form of glycogen (a type of carbohydrate) and fat, most people can safely take breaks from eating. Some evidence shows these breaks can help bodies heal.
You know how some people advise a “Paleo” diet? That means eating like our Stone Age ancestors. Those hunter-gatherers didn’t eat three times a day, because they didn’t have food unless they found it or killed it. Perhaps our bodies evolved to do better if we skip some meals. Here are some fasts that have been studied recently.
Several recent books advocate taking days off from eating. A common schedule is 5:2, meaning five days of normal eating and two days of severe calorie restriction, like 500 calories a day for women and 600 calories a day for men. Books such as The Fast Diet by Dr. Michael Mosley and Mimi Spencer have popularized this approach.
Some people like 5:2 because on your non-fasting days, you can eat normally “with little thought to calorie control.” People should not exercise vigorously or do a lot of endurance training on their fast days. Those who have Type 1 diabetes or who are taking diabetes medicines other than metformin are advised not to try intermittent fasting.
Just 500–600 calories a day is not many, and it’s important to make them healthy calories. Dietitian Amy Campbell reported here that “A sample 500-calorie menu from The Fast Diet is steel-cut oatmeal with ½ cup blueberries for breakfast, and then chicken stir-fry made with 5 ounces of chicken and some vegetables, along with a tangerine for dinner. That’s it.”
Limited hours for eating
The Buddhist monks of Thailand have a rule that they can only eat from waking until noon. They do this for spiritual reasons, so they can focus on enlightenment, but there may be health benefits. According to the UK-based publication The Guardian, Dr. Valter Longo, a biologist at the University of Southern California, practices time-restricted feeding. He allows himself only two meals within three to 12 hours. He says this method is common among people who live to be 100. Limited hours is better than 5:2, he says, “because your system prefers a daily routine, rather than extremes every few days.”
During the month of Ramadan, Muslims will neither eat nor drink between sunup and sundown. They can eat after dark, but their total consumption is usually lower than in normal months.
Other religions have absolute fast days. Jews are supposed to take nothing by mouth from sunset on the evening of Yom Kippur until after sunset the next day. In several traditional religions, fasting is used as a way to spiritual growth.
Professor Roy Taylor’s team at Newcastle University in the UK caused a great sensation by reporting that Type 2 diabetes was completely “reversed” by 8 weeks of eating an 800-calorie-a-day diet. On this diet, people got 200-calorie packets of Optifast, a diet product, three times a day, which contained their needed vitamins and minerals. They could also eat 200 calories of nonstarchy vegetables. You can see some of their vegetable recipes here. No fish or meat, no bread or pasta or dairy products (even full skimmed milk.) No root vegetables like potato or sweet potato. No fruits, no alcohol.
This is not an absolute fast, but it’s not easy. According to the Newcastle team, subjects experienced headache, dizziness, tiredness, hunger, and cold. But they assure that the symptoms improve after two to four days, as your body gets used to burning fat. “It is important to keep up your fluid intake and remember to wrap up warmly,” they advise.
Research shows significant benefits from intermittent fasting. Biologist Valter Longo says that we have evidence that restricting calories lengthens life and reduces cancer, diabetes, and cardiovascular disease in mice and monkeys, “and now we’ve got a lot of evidence for humans, too.”
Dr. Mark Mattson, chief of the Laboratory of Neurosciences at the National Institute of Aging in Maryland, is another strong advocate of fasting. He says intermittent fasting prevents stroke damage. It protects brain cells against Parkinson’s and Alzheimer’s disease and helps them repair damaged DNA. His research is mostly with rodents.
Dietitian Amy Campbell reported here on evidence that, “Intermittent fasting has other health benefits, including reducing inflammation, lowering blood pressure, lowering heart rate, lowering cholesterol, and reducing insulin resistance.”
In Dr. Taylor’s studies, all 11 subjects got off all diabetes medications, but three months after the fast was over, four had symptoms of diabetes again. There has been no long-term follow up. He says it’s important to be sure you really have Type 2 and not an insulin deficiency like LADA or MODY or Type 1 before trying his diet.
Fasting with diabetes
Fasting can be dangerous for people on blood-sugar-lowering medications, such as insulins, sulfonylureas, and meglitinides. According to Erika Gebel Berg, PhD, in Diabetes Forecast, “A study of people with diabetes who fasted during Ramadan found that the risk of being hospitalized for hypoglycemia increased by 4.7-fold in people with Type 1 diabetes and by 7.5-fold in those with Type 2.”
Fasting can also increase risk of dangerously high blood sugar. “With no food,” writes Gebel Berg, “the liver releases stored glucose for energy.” Because people may stop their medications to avoid lows, blood sugar can soar. In one study, “researchers found a fivefold increase in severe hyperglycemia in people with Type 2 who fasted during Ramadan and a threefold increase in people with Type 1.” Fasting is a type of stress, and stress hormones such as cortisol raise blood sugar.
Fasting is almost certainly unsafe if you are pregnant, underweight, or have a history of hypos or ketoacidosis. You have to drink more water and avoid heavy exercise to be safe. Both Islam and Judaism make exceptions for people with health needs to modify their fasts during Yom Kippur and Ramadan.
You might want to consider some form of fasting, but be very careful. If you do, please first consult with your health professionals. Monitor how you are doing and report to someone knowledgeable. Maybe join an online support forum like this or this. And let us know how it goes.
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David Spero: David Spero has been a nurse for 40 years and has lived with multiple sclerosis for 30 years. He is the author of four books: The Art of Getting Well: Maximizing Health When You Have a Chronic Illness (Hunter House 2002), Diabetes: Sugar-coated Crisis — Who Gets It, Who Profits, and How to Stop It (New Society 2006, Diabetes Heroes (Jim Healthy 2014), and The Inn by the Healing Path: Stories on the road to wellness (Smashwords 2015.) He writes for Diabetes Self-Management and Pain-Free Living (formerly Arthritis Self-Management) magazines. His website is www.davidsperorn.com. His blog is TheInnbytheHealingPath.com.
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