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Most of us either weigh too much or are trying not to. So the media happily feeds us a steady diet of tips to keep us from overeating. But some are not quite what they’re cracked up to be.
Plate Size
“Eating off of 8-inch salad plates instead of 10-inch (or larger) dinner plates, and using small bowls instead of large soup bowls can help you feel like you’re still getting a full plate’s worth of food but with far fewer calories,” notes Reader’s Digest.
Does shrinking your plate magically shrink your calories?
“Focusing on plate size is a diversion,” says Barbara Rolls, professor and the Helen A. Guthrie Chair of Nutritional Sciences at Penn State.
“The real problem is the big portions of calorie-dense foods piled on the plate.” (See “Tried and True.”)
In most studies, people don’t eat less when they use a smaller plate.1 Rolls tested plate size in three experiments:2
Adults served themselves macaroni & cheese onto a small, medium, or large plate (roughly 7, 9, or 10 inches across).
Rolls gave each participant the same amount of macaroni & cheese on either the medium plate (with a standard spoon) or the large plate (with a soup spoon).
Participants served themselves from a buffet of five dishes (chicken & noodles, mac & cheese, green bean casserole, broccoli salad, and sweet potato casserole) using a small, medium, or large plate.
In each experiment, people ate roughly the same number of calories, regardless of plate size.
“I’m particularly fond of the buffet experiment,” Rolls says. “If we gave people smaller plates, they just went back to the buffet more times.”
But a smaller plate could help, she speculates, “if you use it as a tool to remind yourself of how much you should be eating.”
More important is what you put on that plate. “Half the food on your plate should be fruits and vegetables that have a low calorie density,” says Rolls.
(Lower-calorie-density foods have fewer calories per bite than foods with a higher calorie density.)
“But if people only have a small plate, they’ll probably give up the foods they like the least, which are often vegetables.”
The Bottom Line: Don’t rely on small plates to help you eat less.
Breakfast Skipping
“Eating breakfast jump-starts metabolism,” declared Prevention.com in March.
“The idea that breakfast is important for weight or that it kick-starts your metabolism is well ingrained,” says Enhad Chowdhury, a teaching fellow at the University of Bath in England.
“And people who typically consume breakfast do weigh less than those who skip.” (Roughly 20 to 30 percent of adults skip breakfast.)
But that’s not proof that skipping breakfast causes weight gain. Something else about breakfast eaters could make them leaner.
To find out, Chowdhury randomly assigned 56 lean, overweight, or obese people to a breakfast group that ate at least 700 calories by 11:00 a.m. or a breakfast-skipping group that ate nothing until noon.3,4
After six weeks, resting metabolic rate and weight were no different in the breakfast eaters than in the skippers. (Presumably, the skippers ate more calories the rest of the day.)
A larger, longer study on 283 overweight or obese adults got similar results.5
“We told participants, ‘Eat something before 10:00 a.m.’ or ‘Eat nothing before 11:00 a.m.,’” says Marie-Pierre St-Onge, associate professor of nutritional medicine at the Columbia Irving University Medical Center.
“There was no difference in weight change after 16 weeks.”
Don’t famished breakfast skippers gorge themselves at lunch? Chowdhury tested that idea by giving 59 adults either a roughly 500-calorie breakfast or no food before lunch.6,7
“When people skipped breakfast, they did eat a bit more at lunch,” Chowdhury says. (“A bit more” averaged 150 calories for lean people and 50 calories for obese people.)
“But it was nowhere near enough to make up for the 500 calories they missed by skipping breakfast,” he says. “They certainly didn’t overeat at lunch.”
However, blood sugar and insulin were higher an hour after lunch when people skipped breakfast. (Insulin tamps down blood sugar by enabling it to enter cells, but cells can be resistant to the insulin.)
“We’re more insulin-resistant later in the day,” says St-Onge. “By eating in the morning, when you’re more insulin-sensitive, blood sugar doesn’t stay in circulation as long.”
The Bottom Line: “There’s not much evidence for the dogma that if you don’t eat breakfast, you’ll suddenly eat a ton of food and gain weight,” says Chowdhury. But eating in the morning may help your insulin work more efficiently later in the day.
Meal Timing
“You are when you eat,” declared NBCNews.com in January.
“A growing number of researchers say limiting the hours during the day when you eat, focusing more on the timing of meals instead of calories, can help dieters burn more fat, improve their health and lose weight.”
In one study, 156 adults used a smartphone app to track what and when they ate or drank for three weeks.8
“People ate around the clock,” says St-Onge, who led a panel of experts convened by the American Heart Association to examine meal timing.9 In fact, there were only five hours—1:00 to 6:00 a.m.—during which people ate very little.8
How might a shorter eating window help people lose weight?
“It hasn’t been studied extensively,” says St-Onge. “But a big part is that it probably helps people cut calories.”
In the smartphone study, people met their calorie needs by about 6:30 p.m. “After that, you’re just tacking on extra calories,” says St-Onge.
What happens when people eat the same number of calories within a short or a long eating window?
To find out, researchers fed eight overweight men with prediabetes all their food during either a six-hour or a 12-hour window, starting at their usual breakfast time (between 6:30 and 8:30 a.m.).10
After five weeks on each eating plan, weight loss and fasting blood sugar levels were no different.
However, the men were more insulin-sensitive and their blood pressure was roughly 10 points lower on the six-hour window plan. And they had less “desire to eat” in the evening, even though they had to stop eating by 2:30 p.m. at the latest.
“The results are interesting from a scientific perspective, but on a public health scale, it’s not practical,” says St-Onge. “Most people want to eat dinner with their family.”
Would a six-hour window later in the day work as well? No one has looked.
But a few studies have pitted early-in-the-day against late-in-the-day eating.
In one, Israeli researchers assigned 74 women with the metabolic syndrome to follow one of two 1,400-calorie diets.11
(The metabolic syndrome includes low HDL “good” cholesterol and elevated blood pressure, blood sugar, triglycerides, and/or waist size.)
The “breakfast diet” front-loaded the day’s intake (700 calories at breakfast, 500 at lunch, and 200 at dinner). The “dinner diet” was more typical (200 calories at breakfast, 500 at lunch, and 700 at dinner).
After three months, the breakfast dieters had lost 19 pounds, while the dinner dieters had lost only eight pounds. (Waist size, blood sugar, triglycerides, and HDL cholesterol also improved more in the breakfast dieters, though that could be because they lost more weight.)
In another study, Iranian scientists randomly assigned 69 women who were overweight or obese to eat 50 percent of their calories at lunch and 20 percent at dinner or vice versa.12 Both groups were told to divide their remaining calories between breakfast and snacks, to cut calories and fat, to eat more vegetables and fruits, and to work toward an hour of exercise five days a week.
Three months later, the “big lunch” group had lost more weight (about 12½ pounds) than the “big dinner” group (about 9½ pounds). And insulin resistance improved more in the big lunch group.
Why might it matter when you eat?
“Our organs secrete hormones at various times of the day,” explains St-Onge. “If you’re not eating in line with those hormones, you could be feeding your body calories at a time when it’s less receptive to them, which may lead to metabolic disorders.”
But a handful of studies isn’t much.
“Research on meal timing is still in the early stages,” says St-Onge.
The Bottom Line: Eating light in the evening may make you less insulin-resistant and might help you shed more pounds.
Mindful Eating
“More and more research points to mindfulness—not certain foods—for weight loss,” ran the Washington Post headline in March.
Mindfulness?
“Mindful eating means that you tune in to hunger signals so you only eat when you’re hungry and stop eating when you’re satisfied,” says Evan Forman, professor of psychology at Drexel University.
“It also teaches people to slow down and to not eat out of boredom or in an automatic, mindless way.”
Can mindful eating help people eat less?
In one study, Forman randomly assigned 55 overweight or obese adults to one of three groups: a control group that got usual healthy eating advice, a mindful eating group, or a mindful decision-making group.13
“Mindful decision-making is about paying close attention to the cues and urges that drive people to eat, and how to make healthier choices in response,” Forman says.
After six weeks, there was no difference in weight loss.
In the largest and longest trial so far, researchers assigned 194 adults with obesity to attend, over 5½ months, 16 training sessions on either diet and exercise alone or combined with mindful eating and stress management.14 After a year, there was no difference in weight loss. Why not?
“We evolved in a world where food was scarce, so we were wise to eat when food was available,” Forman speculates.
The Bottom Line: If mindful eating helps you, use it. But so far, studies don’t find that it leads to more weight loss.
References
1Obes. Rev. 15: 812, 2014.
2Appetite 49: 652, 2007.
3Am. J. Clin. Nutr. 100: 539, 2014.
4Am. J. Clin. Nutr. 103: 747, 2016.
5Am. J. Clin. Nutr. 100: 507, 2014.
6Br. J. Nutr. 114: 98, 2015.
7Int. J. Obes. 40: 305, 2016.
8Cell Metab. 22: 789, 2015.
9Circulation 135: e96, 2017.
10Cell Metab. 27: 1, 2018.
11Obesity 21: 2504, 2013.
12Am. J. Clin. Nutr. 104: 982, 2016.
13J. Contextual Behav. Sci. 6: 409, 2017.
14Obesity 24: 794, 2016.
Tried and True
Studies find that these tips can help you eat less.
Don’t drink your calories. Liquid calories don’t curb appetite as well as solids.
For example, researchers served 120 people a chicken sandwich with either a solid food (watermelon, cheese, or coconut) or its liquid counterpart (watermelon juice, milk, or coconut milk) for lunch. The participants consumed 12 to 19 percent more calories on the days they got the liquids than the solids with their sandwich.1
Downsize. When people are served a larger portion, they eat more.2 Aim for a half cup of pasta, rice, or other grains and a deck-of-cards-size portion of meat, poultry, or fish. Eating at a restaurant? Split a dish with a friend, order a lunch portion, or take half home.
Go low. Fruits and vegetables have a low calorie density—that is, fewer calories per bite—because they’re mostly water. Try replacing some of your cereal with berries or some pasta with veggies or your rice with riced cauliflower.
References
1Int. J. Obes. 31: 1688, 2007.
2Cochrane Database Syst. Rev. 2015. doi:10.1002/14651858. CD011045.pub2.
Photos: SolisImages/stock.adobe.com (top), Jorge Bach/CSPI (plates), stock.adobe.com: Joshua Resnick (woman eating breakfast), danr13 (family dinner), MacroNobre (woman eating with eyes closed), tongpatong (glass of soft drink).