Does intermittent fasting really help you lose weight?

There’s no shortage of diet and fasting plans promising to improve your health. And every year this number increases. These plans share the same goal of helping you lose weight in a way that’s healthy and lasting. Intermittent fasting promises this and even more. According to its proponents, it can reduce your risk of cardiovascular disease, diabetes and even cancer, thanks to a process known as autophagy.

Autophagy: what the miracle of cell renewal has to do with fasting

Autophagy, or autophagocytosis, means «to consume oneself». It sounds scary, but it's actually a small miracle. Through autophagy, our cells renew themselves. «The cell breaks down the body's own resources and recycles nutrients and energy», says Dr. Matthias Riedl, nutritional physician and medical director of Medicum Hamburg (in German only). New cells are then created. But in order for autophagy to have an effect, high-energy foods need to be avoided for an extended period of time. That’s where intermittent fasting comes in.

Approach A or B?

The 16:8 approach

The 16:8 approach usually involves skipping either breakfast or dinner. Food may be consumed during an 8-hour period, which is followed by a fasting period of 16 hours. The exact time frame and what is eaten is determined by each person. «Intermittent fasting according to the 16:8 approach delivers many benefits,» says Riedl, who adheres to this method himself whenever possible. These benefits include a more conscious approach to food and hunger pangs, improved sleep quality and best of all, fasters get to eat anything. Just not during the fasting period. As far as drinks go, you can have them even during the fasting period. Water and unsweetened tea are best, but black coffee is also allowed. You should avoid drinks containing milk, cream, sugar or calories in general – these stimulate the metabolism and would therefore break the fast.

Alternate-Day Fasting (ADF)

«With this option, you eat normally one day, then the next day you're only allowed to eat about 25 per cent of the amount of energy you would normally eat», Riedl says. So you alternate between days when you eat normally and fasting days. What are the advantages? No calorie counting, eating as usual on normal days, and experiencing cravings less frequently.

Is it scientifically proven?

Now that we are familiar with autophagy and some approaches to intermittent fasting, it’s time for the cold, hard facts. What do scientific studies show? Not too much. Studies on intermittent fasting are sparse and their results are at times contradictory.

A team of researchers at medizin-transparent.at (in German only) examined studies related to intermittent fasting and concluded that, «How well intermittent fasting works over long periods of time (more than a year) and what kind of adverse effects it can have – has been, unfortunately, barely if even at all investigated.» Since long-term studies are lacking, many questions remain unanswered. Questions such as: which approaches are effective in the long term? Who can benefit from intermittent fasting? Who can’t?

But at least proponents and opponents agree on one thing. Snacking is unhealthy. It inhibits autophagy from burning energy in fat stores by providing our metabolism with constant fuel in the form of chocolate, chips and whatever else we stuff our faces with between meals. So the first step to healthier eating would be dropping the snacks – even supposedly healthy ones such as fruit and fruit juices.

Recap

If you decide to fast, keep in mind a few things. The German Nutrition Society warns that intermittent fasting could cause muscle loss. «Intermittent fasting can magnify a protein deficiency already existing in the diet», says one nutritionist. The body turns to its own protein reserves when it’s no longer supplied with sufficient protein from the outside. «I always recommend consulting a professional when trying intermittent fasting and restructuring your diet in parallel.»

So talking with your doctor is definitely worthwhile if you’re considering changing your diet. And don’t forget to listen to yourself. «Never choose a diet just because experts recommend it, especially if it’s not a good match for you.»