What the evidence says, and what it does not

It works about as well as cutting calories

In a 12-month trial of 139 people with obesity, eating only between 8 a.m. and 4 p.m. plus a calorie target was compared with the same calorie target alone. Both groups lost weight; the time-restricted group lost 8.0 kg on average against 6.3 kg, a difference too small to rule out chance.¹

A 2025 review of 99 randomised trials reached a similar conclusion across fasting styles: all of them led to weight loss compared with eating freely, and the differences against ordinary calorie restriction were small.²

So why fast at all?

Because it is simple. Instead of tracking every bite, you follow one rule about when you eat. For some people that is easier to live with; for others it is not. The research has not settled who keeps it up for longer, so Metabo does not promise that you will. It shows you, from your own data, whether you are.

Keeping muscle matters

When you lose weight, some of it can be muscle. Eating enough protein and doing some strength training are widely recommended ways to keep more of it. That is why Metabo sets a daily protein target, tracks fat and muscle separately when your scale measures them, and the coach encourages strength training two or three times a week.

What we do not claim

• That fasting treats, reverses or prevents any disease.
• That it is metabolically special compared with other ways of eating less.
• That it “detoxes” you, boosts intelligence, or works through any single hormone.
• That longer fasts are better. Metabo does not run any fast of 24 hours or more without supervision.

How the coach is built

The coach’s advice follows mainstream guidance: start at 12:12 for a few weeks, step up gradually, drink water and unsweetened tea or coffee during a fast, break it with a normal meal with protein and vegetables, and include a variety of vegetables, pulses and fermented foods. Anything involving medicines is left to your doctor.

Sources

1. Liu D, Huang Y, Huang C, et al. Calorie restriction with or without time-restricted eating in weight loss. New England Journal of Medicine. 2022;386:1495–1504. PubMed
2. Semnani-Azad Z, et al. Intermittent fasting strategies and their effects on body weight and other cardiometabolic risk factors: systematic review and network meta-analysis of randomised clinical trials. BMJ. 2025;389:e082007. BMJ