From the Palaeo diet to the 21-day challenge, there's a fad diet for practically everyone. But as fun as they may seem, it's often difficult to stick with them for more than a few weeks, and as a result few people actually see any long-term results.

Rather than trying one of those, here are 15 science-backed habits that can help boost your health and may help with weight loss too.

1. Eat food you enjoy.

It may seem like the easiest way to lose weight is to stop eating the foods you overindulge in. But this can be short-sighted, Lisa Sasson, a New York University nutrition professor told Business Insider. "If you pick a diet with foods you don't like, you're doomed to fail," said Sasson.

Food is a pleasurable experience; if you cut out all the foods you like, you probably won't stick to your plan.

And as studies continue to show, coming up with an eating regimen you can stick with is critical.

2. Portion sizes are key.

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, said Sasson. This phenomenon is why most people in studies lose weight, regardless of whether they're in the group assigned a special diet or not. 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.

3. Skip the restaurant and pack your lunch.

Portion size in American restaurants have doubled or tripled in the last twenty 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.

4. Stick with food that's packed with fibre and protein.

Fibre and protein are two key ingredients to 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", said Sasson. That's why you don't feel as satiated after eating a bag of potato chips as you might after eating a fibre filled baked potato.

In a review of weight loss studies focusing fibre, protein, and fullness, psychologists at the University of Sussex made the case for high-protein and high-fibre foods to be included in weight loss plans because of the benefits feeling full has on preventing overeating and helping with weight loss.

5. Go Mediterranean.

As if you needed more excuses to eat like 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 oversized portions and heavily processed food.

6. Get your calories from food, not liquids.

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 25-50 years old, researchers found that swapping out sweetened beverages with plain old water was linked with weight loss, independent from diet and exercise.

7. Be flexible.

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 aged 22 to 72 on the diets over a one-year period. They found that the people who followed the popular diets were associated with more weight loss and a reduction in heart risk factors than those who didn't stick with the diets.

8. Go with your gut… bacteria.

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.

Want to diversify your gut microbiome? Eat a variety of dairy, vegetables, chicken, fish, eggs, and oils, suggest the study authors.

9. Water is key.

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 (430 millilitres) 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 (1.2 kilograms) more than their study counterparts who did not drink water before meals. Neither of the two groups reported changes in their exercise regimes, either.

10. Never go grocery shopping when you're hungry.

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.

11. A good night's sleep is better than a late-night movie marathon.

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. First, the participants were studied after a week of 9 hours of sleep a night and then after a week of 4 hours of sleep a night.

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

12. Start each day right with breakfast. Your body will thank you.

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 kickstarts your metabolism, the process that breaks down the food you eat into energy.

However, your metabolism responds differently to different types of food. A study published last April showed that in less than a week, a diet high in saturated fat can reduce your muscle's ability to turn the sugar in food into energy.

13. Don't snack after dinner.

short-term study of 29 young men showed that they consumed on average 238 calories less each day for two weeks when they were told not to eat anything between the hours of 7pm and 6am. These calories that they were no longer eating were mostly coming from high-fat, high-carb foods.

14. Avoid diet drinks.

Roughly 20 percent of Americans drink at least one soda a day. If it's regular and not diet that you're drinking, swapping it for diet could lead to weight loss. But studies suggest that change may only work 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 percent greater increase in waist size than people who drank it less regularly or not at all.

While there's no firm 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.

15. Don't go hungry.

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

Although the men lost about a pound (450 grams) a week for the first twelve weeks, they only lost 0.25 of a pound (110 grams) a week for the last half. Worse things happened as well: Many became obsessed with the thought of food, began to lose their hair, and noticed 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 percent 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.

This article was originally published by Business Insider.

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