Intermittent fasting: what is the best method?

Intermittent fasting is a diet method that limits the amount of time you are allowed to eat. The appeal of these diets is that you do not need to count calories or eat certain foods. But there are so many versions that it's hard to know which one is the best. This is what the research says.

The diet 5: 2

This is a popular version of intermittent fasting where you eat a very low calorie diet (about 500 kcal) for two days a week (any two days). The other five days, you eat normally.

Research has shown that it is possible to lose weight with this diet; it also improves several markers of health, such as the reduction of glucose and cholesterol levels in the blood. But it is unlikely that the 5: 2 diet is more effective at losing weight than traditional dieting methods. Indeed, 5: 2 reduces caloric intake to a similar extent to that of a traditional diet.

It has been proven that consuming very low calories in two consecutive days can improve insulin sensitivity, a risk marker for type 2 diabetes, to a greater extent than traditional dieting. This approach also leads to a decrease in blood lipids (fatty substances present in the blood) compared to conventional diets.

An important additional benefit of 5: 2 is that you can consume food during the "fasting" period, thus providing the opportunity to consume essential nutrients. Dieting often leads to loss of muscle and bone mass, as well as body fat, as it is difficult to follow a balanced diet while reducing caloric intake. This can compromise long-term weight loss efforts because the muscle is more metabolically active (burns more calories) than fat. Eating enough protein can help reduce muscle loss during a diet, with a reduction in appetite.

Alternate fast day

5: 2 could be considered a "lifestyle intervention," but fasting over two days is more likely to be used to lose weight fast. ADF is often referred to as a "diet every other day" and requires you to switch daily from an unrestricted diet to a diet with very few calories.

Most ADF research uses a similar 5: 2 approach, allowing a small meal (usually around 500 kcal) to be consumed on "fasting" days. Research has shown that ADF can cause considerable weight loss in 8 to 12 weeks, but one of the big problems with ADF is that adhesion tends to weaken. Longer term studies have shown that caloric intake on days of "fasting" gradually increases over time, reducing the caloric deficit achieved and slowing down the rate of weight loss.

Randomized controlled trials (absolute benchmark for clinical research) show that ADF does not lead to weight loss or health improvement over the traditional diet when caloric intake is the same in both groups. Despite this, it is likely that the ADF will result in a greater reduction in caloric intake compared to traditional dieting methods, which should initially lead to greater weight loss. But it is doubtful that many people adhere to ADF in the long run.

Eating limited in time

Restricted feeding over time (TRE) involves complete fasting for long periods (16 to 20 hours) and the consumption of all calories during a restricted time, often referred to as "window time". ;food".

The most common version of TRE uses a relationship between fasting and 16: 8 feeding (16 hours of fasting and eight hours of eating). Many people reach this ratio by skipping breakfast, delaying their first meal until noon and eating all food between noon and 8 pm.

Research has shown that caloric intake over a 24-hour period is reduced when people skip breakfast. But the number of calories spent during physical activity is also reduced, which will partially or completely eliminate the caloric deficit obtained by skipping breakfast. It is therefore unlikely that skipping breakfast leads to significant weight loss. Skipping breakfast also reduces the effectiveness of insulin to regulate blood sugar after lunch, which indicates a negative effect on insulin sensitivity.

But an alternative approach to TRE has been promising. A recent study showed that fasting from 14 hours improved insulin sensitivity in a group of pre-diabetic men. This could be due to an increased natural ability to effectively regulate blood glucose in the morning, due to daily variations in metabolism. Thus, restricting food intake to a morning feeding window and fasting at night can be a healthier version of the TRE.

And the winner is…

As with any diet, success will be dictated mainly by membership. In terms of weight loss, ADF is likely to lead to the fastest success, but long-term sustained weight loss can be facilitated by the 5: 2 less intense approach.

There is some evidence that adherence may be higher in TRE, since completely restricting food intake may be easier for some people than severely restricting it. In this sense, research suggests that skipping dinner can be better for health than breakfast.

It is important to note that most research suggests that intermittent fasting is not better than traditional diet methods. However, intermittent fasting diets with extended periods of fasting, such as TRE with shorter feeding windows and 5: 2 with two consecutive days of very low calories, may offer additional health benefits.