Healthy Food & Healthy Living by Dr. Ayala

Why taking time to eat can help control your weight

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 at all, 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 small 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

Can gadgets accurately count your calories?

There are very many ways to approach weight control and loss. Tracking calories, our body’s energy coin, is front and center of many of them, as energy deficits will result in weight loss, and energy surplus will result in fat accumulation. Diets that don’t count calories also work on getting to a caloric deficit through other methods. Estimating caloric balance requires knowledge of input and output.

How many calories do you consume?

The traditional way of calculating caloric or energy intake relies on weighing and measuring your food, and knowing the caloric value of each specific food item. There are now apps aplenty – MyFitnessPal, Lose It, and Fitbit to name just a few – that help with assessing portion size and identifying food’s caloric value. It's still tedious, time consuming, and in real life we know that people’s assessments tend to be inaccurate and wishful, erring on the side of underestimating intake.

How many calories do you burn?

Assessing caloric output used to rely on charts taking into account age, gender, body size and activity level – sedentary people burn fewer calories than active ones.

Electronic activity devices are in wide use and are an advanced version of the pedometer, able to measure steps, distance, altitude, and some of them also heart rate. They come in all sorts of wearable and clippable forms. Many of them calculate caloric expenditure by an algorithm that uses our movement and our personal health information, such as gender, height and weight. Most smart phones have a built in health app that provides this info. The Fitbit calculates how many calories you burn, based on what you burn at rest – the calories that are used to maintain vital bodily functions such as breathing, heart and blood circulation, digestion etc. – and the extra calories burned during exercise. The Apple watch provides similar information, dividing calories to active and total calories. 

Is the caloric expenditure accurate? A study from Stanford University looked at six devices (Apple Watch, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2, PulseOn and the Samsung Gear S2) used by 60 volunteers, and although heart rate measures were pretty accurate, energy expenditure measures were off. When compared to metabolic rate assessments measuring oxygen and carbon monoxide in breath – which are a more accurate way to assess energy expenditure – even the most accurate measures were almost 30 percent off, and the least accurate device was off by more than 90 percent. A recent 2020 study looking at four popular wearables (Apple Watch Series 4, Polar Vantage V, Garmin Fenix 5, and Fitbit Versa) also found that heart rate measures were pretty accurate, while energy expenditure measures were unreliable.

So these devices are pretty good at counting steps and heart beats, but not as good at knowing how many calories went by. Mind you I still can’t explain the Samsung bonus: My husband's phone consistently registers an additional 15 percent mileage compared to what my iPhone calculates when we hike together. 

Devices that do the counting for you?

So, the search for an easy, objective way to measure caloric intake is still on.

A promising way to measure caloric intake relies on a simple math equation: Spare calories are stored as fat, so if you knew the energy storage, and you also knew how much energy you expend, you could calculate energy intake. 

As mentioned above, consumer devices that measure physical activity are ubiquitous. 

And there are now devices that claim to measure body composition. Electric scales that use bioelectrical impedance measure not just weight but also body composition (the scale sends an electrical signal through your body that measures the amount of fat vs. lean body mass) and can load this information to your personal account.

Combine the scale information, with the resting and activity energy measures, and you can potentially assess caloric intake without employing tedious food diaries and portion measurements.

How accurate are these measures?

A new study in the Journal of Nutrition compared the results of calculating caloric intake using the commercially available wearable devices for measuring caloric expenditure combined with a smart wi-fi weight scale (Fitbit Alta HR + Fitbit Aria), comparing them to the “gold standard”, the most accurate ways to measure energy expenditure and energy storage. For energy expenditure the most accurate method is doubly labeled water. For measuring storage of fat it’s Dual X-ray Absorptiometry for body composition. These accurate methods are difficult, expensive and require expertise, and are used only in specialized academic centers. This comparison was done for 2 weeks in 24 adult volunteers.

And the results: The Fitbit Aria’s ability to accurately measure fat storage was low. Energy expenditure measurements by the Fitbit device fared better in this recent study, and were quite accurate when compared to the doubly labeled water.

Alas, without an accurate measure of fat storage, the equation cannot be solved, and caloric intake cannot be reliably calculated by the existing electronic devices. 

So it’s back to scales, measuring cups and nutrition labels in order to know how many calories you consume, if you choose to go this route. You can’t base food decisions on these devices – at least not yet.

What’s all this counting good for?

Accurate and convenient automated calorie counting isn’t feasible yet – electronic devices have yet to deliver a reliable solution, even as they’re getting better at it. 

For people trying to eat better, tracking food may be a worthwhile exercise, at least for a while, because it helps you learn what’s in your food, and allows you to moderate caloric intake.

Until you actually count, you may not realize the caloric burden of frappuccinos, sugary drinks and fried foods, and the disproportionate portion sizes served in some establishments.

But once that exercise is over, there are easier and more practical ways to eat well, maintain weight and enjoy life. 

A balanced plate of food (see MyPlate) can be assembled without scales, measuring cups and nutrition charts. And being glued to a digital screen even when you’re out and about outdoors, counting distance and steps rather than looking at the sky and registering birdsong diminishes wellbeing even if it can motivate you to exercise.

Much like with attaining financial literacy, some counting and accounting might be necessary in order to build good habits, but carrying a money or calorie tally in your mind – or on your devices – takes away time and attention that can be better used.

Dr. Ayala