Taking your time to eat helps with weight control

When you slow down you not only eat less, you may also burn more

When I survey my eating habits, which I tend to do especially around the new year, I make note that I should improve my eating speed. How you eat is not as important as what you eat, but it does matter. I notice that when I eat a leisurely meal with company, or when it’s a multi-course one, I feel full halfway through the meal. They say it takes 20 minutes for our brain to register satiety and I certainly experience that.

Yet my natural instinct when I’m eating alone is to wolf things down, which is a pity, as there's no reason to rush through something as pleasurable as eating. 

If you want to eat more intuitively, and regulate your needs based on hunger, slowing down can really help.

Slow down to eat less

A review article in the American Journal of Clinical Nutrition includes 22 studies in which volunteers manipulated eating rate while measuring food intake, hunger, or both. Slower eating was associated with fewer consumed calories no matter how the slower eating was achieved.

Another review and meta-analysis in the International Journal of Obesity compiles 23 studies, and concludes that eating quickly is associated with excess body weight.

A study in the British Medical Journal (BMJ) finds that the odds of being overweight are three times higher in people who report eating quickly and until full. A study in the American Journal of Clinical Nutrition shows that when volunteers took large bites, rather than smaller ones, they ate about 100 calories more of a chocolate custard.

There are many such studies demonstrating that slow eating is a habit associated with moderation in intake and lower rates of overweight and obesity.

But slow eating may not just make you feel full sooner, it may also actually increase your energy spend.

Slow down to burn more?

Eating slowly and chewing thoroughly can increase food related energy spending, also called diet-induced thermogenesis. When our body is engaged in dealing with food – its digestion, absorption, breakdown and storage – it spends energy on it. Is the energy spent when you eat slowly significantly greater?

A study with 11 healthy volunteers had them eating food quickly, swallowing the food as fast as possible, and compared it to eating slowly: chewing the food until there were no lumps in it and only then swallowing it. The metabolic rate was assessed using oxygen uptake. The researchers also measured the blood flow to the abdominal organs. They found that slow meals increased the energy spend – diet-induced thermogenesis – and the blood flow to the gut. The changes were significant, although they may not impress you in caloric count: for a 100 calorie little meal eating slowly spent 6 calories more, and for a 300 calorie eating event the volunteers used 10 extra calories. 

Which doesn’t sound like much, however, multiply the results of the 300 calorie meal trial by 3 daily meals, practice this over a month, and now we’re talking 1000 extra calories burnt just for eating slowly.

Is it chewing that’s burning these calories, is it the prolonged sensory stimulation in the mouth that’s causing increased activity in the gut which takes up more energy, or is it both?

To address this the researchers recently published a follow up in Scientific Reports in which volunteers consumed liquid food that doesn’t need chewing in three different settings: in the control they swallowed 20 ml of a cocoa drink every 30 seconds without it lingering in the mouth, in the second setting the volunteers kept the fluid in their mouths for 30 seconds and then swallowed it, and in the third trial they kept it in the mouth and fake chewed it for 30 seconds before swallowing it.

And the results: the duration of tasting the food, and the duration of chewing both increased energy needs as measured by oxygen uptake. The blood flow to the gut also increased in both test groups.

Chewing liquid food, which obviously doesn’t need to be broken down in your mouth, uses fewer calories. The 200 calorie beverage in this trial burns an additional 2 calories when it lingers in the mouth, and 4 more if it’s also chewed. Chewing drinks is not something people do in polite society. Chewing chunky food is what makes a small but cumulative difference.

The authors conclude: “slow eating, which involves chewing food slowly and thoroughly, increases DIT (diet-induced thermogenesis) and may be an effective strategy for preventing overweight and obesity.”

Add the energy burning bonus to the effects on appetite and satiety and eating slowly makes more and more sense.

Tips for slowing down

• Share meals: We’re on our best, most polite behavior when in company, and family meals are important in so many ways.

• Sit at a table: Eating on the go, in front of a screen or over the sink makes you gobble food real fast.

• Solid calories are better: Food that doesn't need chewing goes down fast. Minimize liquid calories (sweetened drinks) and highly processed foods that dissolve in your mouth. The more fiber in your food, the more chewing it demands.

• Try small courses: Not to suggest that you need to prepare several courses, tasting menu style – you can serve yourself a smaller amount of one course, take a short break, and then consider seconds.

• Chew: I don't suggest counting to the 32 suggested by The Great Masticator, or counting at all, but keeping food in your mouth a tad longer and not swallowing it whole is helpful.

• Let go between between bites: Put down your fork; same goes for letting go of hand-held foods such as pizza or apples between bites.

• Drink in between: Sipping water with your meal slows you down, and at the same time distends your stomach, sending satiety signals to your brain.

Changing eating behavior isn’t easy, and if small, slow bites aren’t in your nature, think about what triggers your own fast eating – is it screen distraction, eating by a computer, hunger? Address that trigger and repeat the behavior again and again to make the new habit stick.

Dr. Ayala