Researchers say the report holds promise for the popular diet as a diabetes treatment.
Could putting a scale on your diet for a couple of days a week put type 2 diabetes in regression? That’s the controversial claim scientists of a small new study are making as they blow the fire around a diet fad known as intermittent fasting. But numerous health professionals, including those at the American Diabetes Association, argue that the approach can be dangerous for people with diabetes, whose bodies cannot control their blood sugar without careful diet, medication, and sometimes insulin management.
In the study, published October 9, 2018, in the journal BMJ Case Reports, intermittent fasting, in which eating is limited during certain times of the day or week, reportedly helped three middle-aged men with type 2 diabetes lose weight, get off their insulin, and reduce or get off their oral medication.
“The real problem is we don’t see diabetes as a dietary problem; we treat it with a lot of drugs, and that never addresses the root problem of the diabetes,” says principal investigator Jason Fung, MD, a kidney specialist at Scarborough and Rouge Hospital in Toronto, Canada, and author of The Complete Guide to Fasting,and The Obesity Code, a 2016 book thought to help popularize intermittent fasting.
The Effects of Intermittent Fasting on Weight and Blood Sugar
Around 90 percent of people with type 2 diabetes are obese or overweight, according to the Obesity Society. Weight loss is a known treatment for type 2, which affects the majority of the 30.3 million people with diabetes, as it helps people with the disease reduce insulin resistance and absorb blood glucose more effectively. According to the Centers for Disease Control and Prevention (CDC), being overweight makes it harder to control diabetes and is a risk factor for diabetes-related health complications.
The grandmark of type 2 diabetes is insulin resistance, a condition in which the cells, muscles, and liver can’t effectively absorb glucose (blood sugar). This causes hyperglycemia (high blood sugar), and in serious cases requires medication, such as Glucophage (metformin) and insulin, to lower.
Just a regular calorie restriction through any diet can lead to weight loss and make it easier to manage blood sugar. Intermittent fasting is thought to go a step further by lowering serum insulin, which triggers the body to burn stored sugar, called glycogen, along with fat, in the absence of glucose from food, Dr. Fung says. These processes (called glycogenolysis and lipolysis, respectively) can temporarily lower blood sugar and cause weight loss.
How Intermittent Fasting Affected Men in the Study
For the study, Fung and his team randomly recruited three men, ages 40 to 67, with type 2 diabetes, who also had high cholesterol and high blood pressure. At the beginning of the study, the authors recorded the participants’ vitals, including their A1C (a three-month average of their blood sugar levels), their fasting blood glucose levels, their waist circumference, and their weight. All three men were on insulin and oral medication.
The men took a six-hour educational course on diabetes and intermittent fasting prior to fasting. For the experiment, one man fasted for 24 hours three days per week, and the other two alternated their fasting days throughout the week. On fast days, they ate one low-calorie meal in the evening, and drank low-cal beverages, such as water, coffee, tea, and broth. The authors encouraged participants to opt for low-carb on the eating days.
Two times per month, Fung and his colleagues observed the participants, and adjusted their insulin and medication to help prevent episodes of hyperglycemia and hypoglycemia (low blood sugar).
Eighteen days into the study, all three men lost 10 to 18 percent of their body weight, trimmed their waist circumferences, no longer had to take insulin, and reduced their oral medication. (Two of the three men completely got off their medication during this time frame.)
“In all cases, their blood sugar was actually better at the end than the beginning despite not taking medication, which tells you the diabetes is reversing,” says Fung, adding that the participants maintained their improved vitals for about a year total.
Why It’s Too Soon to Recommend Intermittent Fasting to Treat Type 2 Diabetes
One of the reasons intermittent fasting is so controversial is that there are limited large-scale human studies that prove it’s safe and effective in humans long term, says Robert Gabbay, MD, PhD, chief medical officer at Joslin Diabetes Center at Harvard Medical School in Boston.
One such study, published in July 2018 in the Journal of the American Medical Association, found that intermittent fasting was no better at improving type 2 diabetes participants’ blood sugar levels than regular caloric restriction after one year. Previous studies on mice suggest intermittent fasting may improve memory, reduce disease risk, and aid with weight loss, according to an article published in June 2013 in the journal CMAJ, but, as Dr. Gabbay points out, “That doesn’t always translate to people.”
Yet Gabbay says preliminary human studies with positive results, like this week’s in BMJ Case Reports, suggest the diet is worthy of further study in a larger population over a longer period of time. For now, he cautions people with diabetes, especially those on insulin and sulfonylureas to lower their blood sugar, against trying intermittent fasting before speaking with their healthcare provider.
Fung agrees, saying medical supervision is key when fasting and managing diabetes. “If you’re on medication, you have to talk to your doctor because they’re the ones who are going to guide you. We were the ones who guided these patients,” Fung says.
A Look Ahead at Possible Intermittent Fasting Research
Because of the small size of the current study and the potential health risks of intermittent fasting (high and low blood sugar, among them), Gabbay says it’s too soon to officially recommend intermittent fasting for diabetes treatment. He is also skeptical about the sustainability of intermittent fasting.
“The goal is to really have sustained weight loss, and for some, this (intermittent fasting) might be a difficult long-term pattern of eating, which is what one really needs to do for maintaining weight,” Gabbay says.
Fung hopes to conduct a longer-term, large-scale study, but he isn’t sure when his team would receive approval. “We’ve had to fight to get even this published,” he says.
Fung argues that institutional medicine considers fasting harmful despite its regular use in medicine (prior to colonoscopies, for example) and its use in certain religions, such as during Ramadan in Islam. But that may be different in the future.
“Public interest in fasting has sort of exploded,” Fung says, “and I’m hoping that starts to change these entrenched attitudes that fasting is intrinsically harmful to us.”