Overeating and obesity are risk factors for insulin resistance and type 2 diabetes, so you’d be forgiven for thinking that abstaining from food could help fix the problem. While the situation is much more nuanced, there’s certainly cause for considering an intermittent fasting (IF) regime, since both experimental and clinical studies have shown that the dietary approach improves insulin sensitivity and glucose control along with modest decreases in body weight.
In a 2017 study, researchers from the University of Southern California put 100 people through a series of 30-day cycles of periodic fasting. After just three cycles — each with 25 days of unrestricted eating and five days of restricted eating — participants who started the trial with high blood sugar saw big improvements without experiencing any harmful effects. The findings build on previous research where mice with diabetes were cured after similar interventions.
In July, researchers from the German Centre for Diabetes Research showed that mice on an IF regimen also exhibited lower pancreatic fat, which is thought to contribute to the development of type 2 diabetes. In October, the British Medical Journal published case notes of three men with type 2 diabetes who reversed their dependence on insulin, lost weight and improved levels of HbA1C, a measure of blood sugar levels, while following an IF regime.
“Most patients with type 2 diabetes are obese, and weight loss plays major role in the management of type 2 diabetes as it decreases the insulin resistance,” says Dr Mohamed Nabil Mahna, Specialist — Endocrinology at Medcare Hospital Dubai. “IF lowers serum insulin levels which trigger human body to burn fat and stored sugar. These processes can lower blood sugar and cause weight loss.”
Dr Wafaa Ayesh, Director of Clinical Nutrition at the DHA, hears a lot about IF. “Since obesity commonly coexists with type 2 diabetes, there is evidence that this type of fasting may also slow the progression of type 2 diabetes in obese individuals,” she says, while sounding a note of caution. “Although short-term studies have showed positive findings, more long-term studies are required to support this approach.” She’s got a point: IF’s long-term effects remain unknown.
Better Health looks at what the concept means, and its pros and cons.
What’s intermittent fasting?
Before you embark on an IF regimen, though, it helps to understand what exactly it is, given how trendy the practice has become recently. “IF involves restricting energy intake on one to three days per week, and eating freely on the non-restriction days,” explains Dr Ayesh.
Calorie restriction takes various forms. The 16:8, 18:6 or 20:4 plan requires abstaining from all food (not water) for 16, 18 or 20 hours, and eating only 500 to 600 calories during non-fasting hours. The 5:2 diet involves reducing your calorie intake on two non-consecutive days each week — 600 kilocalories for men and 500 kilocalories for women. The other five days, men need to eat 2,500 kcals worth of food, and women 2,000 kcals worth. Finally, alternate-day fasting consists of a fast day where you eat 25 per cent of your normal food intake on alternate days while eating as much as you want on other days. What they all have in common, though, is that while food is not allowed during fasting periods, you can have black coffee, tea and other non-caloric beverages.
So I can’t really eat anything at all on non-fasting days?
You’ve got that right. What you eat matters just as much as how you eat. Dubai-based doctor and nutritionist Dr Remy Shanker says IF works can even improve body composition by reducing body fat percentage while improving lean body mass — if you pick the right protein and fat sources. “The quality and quantity of what one eats during the window of feeding is extremely important. While it is super convenient and easy to follow with no calorie counting, knowing what’s on your plate is the game changer. Indulging in refined carbohydrates and processed foods eventually leads to excess blood sugar that gets stored as fat. So when you can’t stop eating, you go into the infamous stock up mode, triggering the vicious cycle of eating with no end and zero satiation, which can wreck the cycle of IF.” The perfect recipe, she says, is eating healthy fats combined with lean protein, wholegrain carbohydrates and green, cruciferous vegetables. “One can even reverse the condition and get the HbA1c to a value below 5 and stay at it without any glycaemic control pills by just practicing IF, basic good cooking and educated food choices.”
How does intermittent fasting work?
IF weight loss is thought to be the result of lowered appetite or burning more calories. After a small study of 11 men and women, however, American researchers showed this June that IF increased fat-burning, decreased appetite and decreased levels of the hunger hormone, ghrelin. Whether these are the only reasons IF works remains to be assessed.
What are the negative aspects of IF?
Dr Kingini Bhadran, Specialist Endocrinologist at Aster Clinic in Al Qusais, says IF isn’t for everybody. “People on insulin, sulfonylureas and other diabetes medications cannot safely do intermittent fasting because of the risk of hypoglycaemia. With long-term intermittent fasting, one needs to also be concerned about protein, vitamin and mineral malnutrition.”
Additionally, IF is hard to follow over the long term, and human studies report high dropout rates. Fasting for a long period is hard work, and people like to reward themselves afterwards, which can lead to overeating, Dr Ayesh says, quoting Dr Frank Hu, chair of the nutrition department at the Harvard T.H. Chan School of Public Health. Human biology conspires to push us to overeat following fasting periods, she adds, since our appetite hormones and the brain’s hunger centre go into overdrive when we’re deprived of food. Dr Shanker adds one more caveat: IF is certainly not recommended for those with an eating disorders or disordered eating patterns.
But some people say I shouldn’t skip meals?
Dr Mahna is one of them. “Skipping meals can slow down metabolism as it may cause your body to crave food which causes you to eat a lot. Eating breakfast helps start the body’s burning process, and five or six small meals a day prevents the metabolism from slowing down. Eating five or six times, including snacks for type 2 diabetic patient, is good for blood sugar control, because carbohydrates are being divided all over the day.”
On the other hand, Dr Bhadran says your metabolism doesn’t slow down if you don’t take the grazing approach. She says your body goes into starvation mode only after a long period, which is why doctors say you shouldn’t fast on consecutive days. “It takes about three days of complete fasting or very low calorie restriction for your body to do something as drastic as down-regulating your metabolism,” she says. Additionally, she adds that what you eat matters because of food’s thermic effect — the number of calories expended to digest food. “Again, the thermic effect of food is identical — whether you ate three times, five times, or ten times because it is based on the total quantity of food, and not on the frequency of food intake.”
So IF isn’t for everyone?
While intermittent fasting works for many people, not everyone can handle the tremendous physical and psychological demands. And that’s all right. Diabetes management depends on the individual, something that holds true for dietary approaches too, explains Dr Mahna. “Diet varies from individual to another. Some require different types on food and nutrition. It depends on the age, gender, lifestyle, health and genetics. The right mix of carbohydrates, proteins, vitamins, fats and minerals ensures that human body is healthy, and its immune system is strong to combat against diseases. There is no single formula can work for everyone and also that varies from time to time in the same person.”