Chew your deep-dish filled-crust pizza slowly. Slurp your thick shake with care. Do not pour cooking oil down your neck to act as a slide for your next Cinnabon.

Eat slowly. Get thin. This is the promise underlined by researchers at Japan's Kyushu University, who pored over the data of 60,000 Japanese health insurance claimants.

Slow eaters were 42 per cent less likely to be overweight or obese than fast eaters. Even normal-speed eaters had a 29 per cent lower risk of being overweight.

"It's all to do with the signal to the brain," explained performance nutritionist Elly Rees.

"Studies show that it takes up to 20 minutes for us to register that we're full. So people who overeat tend to eat too quickly."

That 20-minute gap can be vast. If people eat more slowly, they "find that they're actually full", Ms Rees said.

While many of us might think that we have evolved to guzzle food as fast as we can, there are a range of ways to break the habit.

Many nutritionists recommend putting down your utensils between bites. Others suggest drinking a glass of water before a meal - "a lot of hunger is mistaken thirst", Ms Rees suggested.

Talking works, too. The best advice for most of us is simply not to eat in front of screens. Simply looking at our food helps the brain feel full.

Chewing is the point at which scientific advice and "not looking weird" collide.

Many dietitians suggest that hard foods - meats and vegetables - should be chewed 20 to 30 times. Others have it pegged at the curiously precise 32.

Finally, while chewing hard, replacing your utensils, and mindfully venerating what's on your fork go some of the way, it's also a good idea to eat foods that are tricky to swallow.

A 2011 study suggested that pistachio eaters who ate unshelled nuts consumed 41 per cent less than those who ate shelled ones, but felt just as full.

Basically, eat anything with a shell or an exoskeleton, or anything that is still clawing at you as you gnaw it down.

THE GUARDIAN