Eat early to burn more: why meal timing changes everything

Neuroscientist Frank Scheer's team at Harvard Medical School set out to understand why late meals might promote fat storage. To do this, they conducted a highly controlled study on 16 overweight or obese participants, under two distinct conditions:

• In the first, meals were taken at 9 am, 1 pm and 6 pm.
• In the second, they were staggered to 1 p.m., 5 p.m. and 9 p.m.

The results? Three major effects were observed:

1. Metabolism slows down: the body burns fewer calories after a late meal.
2. Hunger increases: levels of the satiety hormone leptin fall when eating late.
3. Fat storage intensifies: genes involved in the creation of new fat cells (adipogenesis) become more active, while those involved in fat breakdown (lipolysis) become quieter.

In short: eat late = burn less, store more.

Our metabolism functions according to an internal biological clock: the famous circadian rhythm. This "clock" regulates everything from body temperature to hormone production. And it doesn't like to be disturbed.

Eating late is a bit like feeding the body when it's already getting ready to sleep. Result:

• Digestion is slower.
• The body expends less energy.
• Satiety signals are disrupted.

According to the study, even with identical caloric intake and equivalent sleep, volunteers who ate at 9pm burned less fat than those who dined at 6pm.

"These results show that mealtime influences human physiology, independently of other lifestyle factors", says Frank Scheer.

According to observed data, the key moment is before 7 p.m. for the majority of individuals. Eating earlier in the evening gives the body 3 to 4 hours to digest before bedtime, helping to regulate blood sugar levels and burn fat.

But beware: it all depends on your lifestyle too! If you go to bed late, dinner at around 8 p.m. is perfectly acceptable, but the key is to avoid eating just before going to bed.

Don't panic, there's no question of revolutionizing everything overnight. Here are a few tips validated by dieticians to limit the impact of late meals:

1. Lighten up on dinner: opt for lean proteins (fish, tofu, eggs), vegetables and fiber, rather than dishes rich in carbohydrates or fats.
2. Avoid fast sugars in the evening (desserts, juices, sweet cereals). They encourage insulin spikes, and therefore storage.
3. Listen to real hunger, not habit: sometimes, we dine late because we've "always done it this way", not because we're hungry.
4. Get moving after your meal: a 10-15 minute walk helps to regulate blood sugar levels and activate the metabolism.

Another interesting observation is that eating late also disrupts sleep quality. Digestion mobilizes energy and raises body temperature, while sleep requires exactly the opposite.

Poor sleep is itself associated with easier weight gain: it disrupts the hunger (ghrelin) and satiety (leptin) hormones. A real vicious circle!

"Eating earlier also means getting a better night's sleep - and better regulating your appetite the next day", say the researchers.

• Eating late slows down fat burning,
• Increases feelings of hunger,
• and stimulates fat storage by activating certain genes.

The body prefers an early, light and regular dinner: between 6 and 7:30 p.m., ideally.

So, tonight, if you're hesitating between "one more episode" or "set the table now"... you know what to do ;)