15 healthy eating habits that work, according to science

There's a psychological component to eating, especially when you have weight loss in mind. Being conscious of losing weight and sticking to the right portion sizes is half the battle, Sasson said. This phenomenon is why most people in studies lose weight, regardless of whether they're in the group assigned a special diet. Simply being studied can lead to people being more conscious of what they're eating.

But overall, keeping an eye on portion sizes is a great way to help avoid overeating — especially with portion sizes rising since the 1970s.

Portion sizes in American restaurants have increased by as much as three times in the past 20 years, and it is changing what we think of as a normal meal.

"One way to keep calories in check is to keep food portions no larger than the size of your fist," Elizabeth G. Nabel, director of NIH's National Heart, Lung, and Blood Institute, writes.

If you're trying to control your portion sizes, it is best to pack your own lunch because restaurants will give you more calories than you need.

Fiber and protein help keep you feeling full. Processed foods like candy bars and cookies are often low in both of these ingredients and instead are "readily absorbable," Sasson said. That's why you don't feel as satiated after eating a bag of potato chips as you might after eating a fiber-filled baked potato.

In a review of weight-loss studies focusing on fiber, protein, and fullness, psychologists at the University of Sussex made the case for high-protein and high-fiber foods to be included in weight-loss plans because feeling full can help prevent overeating and spur weight loss.

As if you needed more excuses to eat as if you live on the Mediterranean (olive oil, pasta, hummus, tomato, and cucumber salad — what's not to love?), studies have shown that a so-called Mediterranean diet may help reduce the risk of heart disease and provide some potential memory-related benefits. And a recent study also found a link between the eating plan and a lower risk of breast cancer in older women.

According to Sasson, there may be an overlooked element of the Mediterranean diet: It may not be so much about what the people who live around the Mediterranean Sea are eating, but rather about what they're not eating, such as oversize portions and heavily processed food.

Juice and soda may taste better than plain old water, but the calories inside them can add up.

In a study of 173 obese women ages 25 to 50, researchers found that swapping out sweetened beverages with plain old water was linked with weight loss, independent from diet and exercise.

Sasson says having an eating plan with flexibility is key. Weight Watchers, for example, allows for a variety of different meal types. Having options for what you can eat can makes it easier to build that into your life, as opposed to a diet that sticks to the same five meals every week.

In a study of diets like Weight Watchers and Atkins that allowed for such flexibility, doctors and dietitians at Tufts University looked at 160 overweight people ages 22 to 72 on the diets over a one-year period. They found that the people who followed the popular diets saw more weight loss and a reduction in heart risk factors compared to those who didn't stick with the diets.

The microbes that live in your stomach, collectively called your microbiome, play an important role in digestion. In a recent study, researchers in Sweden came up with a mathematical formula to help find the right eating plan for each person based on his or her microbiome. The study authors found evidence that these plans could help the participants lose weight and even possibly prevent certain diseases.

This research is still preliminary, so beware of diets that suggest there's some kind of magic formula for your microbiome. But if you want to diversify your gut microbiome, here's some simple advice that makes for healthy eating either way: Eat a variety of dairy, vegetables, chicken, fish, eggs, and oils, the study authors suggest.

Eating when you're very hungry can make you more likely to overeat.

One possible way to stave off this problem may be as simple as drinking at least 16 ounces of water about 30 minutes before your meal. A small study found that people who did this before at least one meal a day lost 2.7 pounds more than their study counterparts who did not drink water before meals. Neither of the two groups reported changes in their exercise regimes, either. (Needless to say, exercise has many, many benefits and should be incorporated into all healthy lifestyles; but moderate exercise is often enough — and won't leave you famished.)

One small study found that hungry shoppers grabbed one-third more junk food than full shoppers. So, just make sure that you're aware not only of what you're eating, but also of what you're buying.

Beware the cravings that can come with feeling sleepy.

Researchers using functional magnetic resonance imaging (fMRI) scanned the brains of 25 men and women of average weight as they looked at images of delicious, fatty junk food. The participants were studied after a week of nine hours of sleep a night and then after a week of four hours of sleep a night.

When the participants were well rested, the reward centers of their brains didn't react nearly as much to the junk food photos as when they were lacking sleep, suggesting that we're subconsciously more attracted to fatty foods when we're tired and need energy.

There's a saying that breakfast is the most important meal of your day, and it may be true. Evidence suggests that an early meal kick-starts your metabolism, the process that breaks down the food you eat into energy. There's been a lot of back-and-forth on the topic, and a study published in July didn't see any effects of eating breakfast on the kids' ability to perform in each of the cognitive tests compared to kids who had not eaten breakfast.

But, of course, breakfast does provide vital nutrients to keep you energized throughout the day, so if you do eat breakfast, it's important to eat a morning meal that's high in protein and complex carbohydrates, but low in sugar.

A short-term study of 29 young men showed that they consumed on average 238 fewer calories each day for two weeks when they were told not to eat anything between 7 p.m. and 6 a.m. And these calories they were no longer eating were coming mostly from high-fat, high-carb foods.

Roughly 20% of Americans drink at least one soda a day. For those drinking regular, switching to diet could lead to weight loss. But studies suggest that change may work only in the short-term.

In a study that ran from 1979 to 1996, researchers found from a sample of nearly 750 people age 65 or older, that those who drank diet soda on a daily basis had a 70% greater increase in waist size than people who drank it less regularly or not at all.

While there's no evidence to support the scary notion that artificial sweeteners increase our risk of cancer, there is reason to suspect that in the long run it won't help your waist line. Still, while these studies show only an association between drinking diet soda and putting on weight, you can't go wrong switching from a highly processed beverage to plain old water or seltzer.

At the end of World War II, researchers starved 36 young male volunteers for 24 weeks, giving them a low-fat diet limited to just 1,600 calories a day, which was 600 to 1,500 calories fewer than their body needed (depending on their level of daily activity) to maintain a healthy weight.

Though the men lost about a pound a week for the first 12 weeks, they lost only one-fourth a pound a week for the last 12 weeks. Worse things happened as well: Many became obsessed with the thought of food, began to lose their hair, and noticed that their wounds seemed to heal more slowly.

When the men were finally allowed to eat freely, many went on extreme binges, consuming as much as 10,000 calories a day — five times as many calories as they needed. Twenty weeks after freedom the men had gained an average of 50% more body fat than when they began the study.

You cannot go hungry forever, and your body doesn't want you to, so be smart about losing weight. First, know how many calories your body needs with online calculators like this one from the Mayo Clinic, and then reduce your caloric intake moderately.