Is time-restricted eating or intermittent fasting better for controlling type 2 diabetes than following a calorie-restricted diet? A recent study published in the “Nature Medicine Journal” suggests that time-restricted eating had a modest effect on postprandial blood sugar after six months than calorie restriction in adults at higher risk for type 1 diabetes. 2.
Explaining the study, Dr Atul Luthra, Director and HOD, Fortis C-DOC, Center of Excellence for Diabetes and Metabolic Diseases, at Fortis Memorial Research Institute, Gurugram, says the process of fasting has always been known to eliminate toxins from the body. However, early time-restricted eating combined with intermittent fasting is preferable to total calorie restriction, as the former compresses meal times and prevents late-night binge eating.
Early diet or calorie restriction, which is better to reduce the risk of diabetes?
I would like to share two historical facts. Religious fasting has been practiced for centuries to cleanse the body and rid it of toxins. Our ancestors followed circadian rhythms for eating, prioritizing heavier food intake at the start of the day and finishing all meals at sunset. Now we talk about similar concepts and call them intermittent fasting, time-restricted eating, or calorie restriction.
Time-restricted eating means eating or consuming energy within a specific window of time or compressed meal times. On the other hand, we have continuous calorie restriction known as CR, where you limit the total number of calories you consume in the day, bringing it down to 70% of your normal intake without any time restrictions.
Which diet is good for whom?
Both are good strategies, but we need to understand what is good for whom. Calorie restriction is basically a method of reducing the intake of calories and burning more of them through physical activity and exercise. The goal could be weight management, changing body composition, or reducing body fat. Thus, calorie restriction can be used for weight management, fat burning, and changing body composition.
Intermittent fasting is intended for a subset of people who are at high risk for diabetes in the future, either due to genetic factors or due to certain clinical parameters. Why does it work? This is because our basal metabolic rate drops in the evening and we tend to burn fewer calories. As our activity level decreases at that time of day and our unspent calories are stored, insulin resistance increases. Additionally, we have more cravings in the evening due to a change in our nutrient signaling pathways. Thus, leptin, the satiety hormone, decreases and ghrelin, the appetite-stimulating hormone, increases. With declining metabolic rate and exercise levels, cravings for nutrients increase and insulin resistance becomes higher, factors that are not conducive to diabetics. So if you compress meal times into a specific window of about eight hours, having your first meal at 10 a.m. and your last meal at 6 p.m., commonly referred to as a time-restricted meal, you can avoid a calorie load by late evening from building upstairs.
The other method is the alternate day fast where one day you have unlimited food and the other day you only take in 30% of your normal calories, that too within a four hour window.
Which diet is best for diabetic patients?
When it comes to diabetes prevention or glucose metabolism, time-restricted eating is definitely better than total calorie restriction for suppressing insulin resistance factors. Thus, diabetic patients should avoid eating late at night. This applies not only to people with diabetes, but also to people predisposed to later developing diabetes or prediabetics.
What about those who want to lose weight? What diet should they follow?
For someone who is a teenager, who doesn’t have diabetes or cholesterol issues but just wants to lose weight, the focus should be on total calorie restriction. Calorie intake is determined by your body weight and activity level. Once you figure this out, you should only take in 70% of your required number of calories. This will help with weight management, body composition and fat mass as well as inch loss. Calorie restriction is basically creating a positive balance toward calorie expenditure rather than calorie intake.
Which age group needs calorie restriction the most?
I would recommend it for teenagers as they have very bad eating habits, are fond of fast and processed foods high in fat and low in fibre. They should have more protein, complex carbohydrates, and less simple sugars and saturated fats.
Middle-aged people are prone to diabetes and should opt for a time-restricted diet. For older people, calorie restriction works because they tend to gain weight.
What about those who have no choice but to go to bed late at night, eat late, but want to lose weight and not develop diabetes?
Then you follow this old principle: eat breakfast like a king, lunch like a commoner, and dine like a beggar.
What are the negative impacts of these diets?
When we talk about intermittent fasting which consists of restricting meals between 10 a.m. and 6 p.m., then the practitioner may feel tired late at night. One may also report trouble sleeping, developing constipation and midnight cravings for food. For diabetics, the management of medications, which must be taken twice a day 12 hours apart, can become problematic.
Suppose a diabetic takes a pill at 6 p.m. but without a meal after that, the person’s sugar level may drop. Thus, matching medication intake with eating habits is a difficult discipline to follow.
Why Dr. Luthra?
Dr Atul Luthra, Director and HOD, Fortis C-DOC, Center of Excellence for Diabetes and Metabolic Diseases, at Fortis Memorial Research Institute, Gurugram. He is also a faculty member of the diabetes education course certified by the British Medical Journal and the Royal College of Physicians.