Humans have practiced fasting since time immemorial. Recently there has been a resurgence of interest in intermittent fasting (IF). IF is practiced in many ways, including fasting on alternate days, twice a week, 5 consecutive days a month and others. However, the most popular form is the concept of 16-hour fasting daily- which means that you confine eating to 8 hours every day. So if you have your breakfast at 8, your last meal has to be at 4 pm. And for the remaining 16 hours, you observe near abstinence from food.
While the benefits claimed for IF are numerous, most people want to use it as a tool for weight loss. Conceptually IF is truly not about what you eat, but about when you eat. It shifts the focus from food composition to food timing. It is based on the understanding that if we starve our body of calories for prolonged periods; the body tends to break down body fats resulting in weight loss.
Some people find IF easier to follow than usual low-calorie diets. There can be hunger pangs initially, but they tend to settle after a few days. IF can be a realistic and effective approach for weight loss and diabetes prevention. It can lessen inflammation, and may even enhance brain function. Weight loss per se depends more on the total calorie intake over 24 hours rather than the timing. However, improvement in metabolic parameters is much greater with IF.
The best results with IF seem to be when we mimic our natural body clock, i.e. eat in the day and fast at night. Most studies have used 7 am to 3 pm as the eating window. It is likely that 8 to 4, or 9 to 5, or even 10 to 6 will work. But it is unlikely that a pattern of eating through the night and fasting during the day will give similar results, as it contradicts our normal body rhythm.
Despite the concept being based on timing rather than food composition, the best results will only be seen if we avoid high sugar, high fat, calorie-dense food and stick to fruits and veggies, fiber, healthy protein, and healthy fats. Snacking is a total no-no.
Not everyone is a candidate for intermittent fasting, and please talk to your doctor before you embark on this path, especially if you are on anti-diabetic medication.