You finally hit your goal weight, so now you can (finally) go ahead and enjoy that cookie after lunch. Or can you? If you don't want the scale to leap back in the opposite direction, you're better off sticking to lean meats, Greek yogurt and other sources of protein.

While it's true that you can maintain your weight on more calories than the limits you had when dieting, new preclinical research published in Nature Metabolism suggests that eating a high-protein diet after a calorie-restricted diet gives you a better chance of keeping the weight off.

"Our results provide insight into the mechanisms underlying fat mass increase after dieting," the authors wrote.

Why does weight rebound?

The study, led by Wuling Zhong of the Shanghai Institute of Nutrition and Health at the University of Chinese Academy of Sciences, was conducted on mice who had been given calorie-restricted diets to decrease their body fat. The mice who returned to their feeding habits of eating whatever they wanted quickly accumulated fat mass. Note this doesn't mean going hog wild (or "mouse wild") or binging; the subjects simply ate the types of foods and quantities they did pre-diet.

Not only that, but researchers found that even when they fed the mice a controlled diet after ending their calorie-restricted diets, the mice still quickly accumulated fat mass. Why? The study found that returning to a full-calorie diet led to dysregulation of fat metabolism and accumulation of fat in the liver. So the mice might have eaten the same amount of calories as before, but their bodies absorbed more fat (lipids) from the food than it did before the diet.

The parallels between the mice's weight patterns and human experience abound. We tend to diet intensely, lose a lot of weight quickly, then gain everything back when we start eating "normally" again.  And similarly for humans, even "watching what you eat" after a weight loss diet (with what's often called the "maintenance phase") may not help avoid that rebound weight.

But there is hope! The researchers found that when mice were re-fed with a high protein diet, they did not quickly gain fat mass, and they even partially maintained the weight loss from the dietary restriction phase. High-protein diets also prevented the increased fat absorption and fatty liver seen in the other mice.

Why protein helps maintain weight

According to this mouse study, high protein intake helped to maintain the weight loss achieved in the calorie-restricted diet by blocking intestinal absorption of lipids, or fat. This effect is also seen in humans—a meta-analysis in 2019 showed a significant beneficial effect of higher protein intake on the prevention of weight regain.

High protein foods are good for helping you feel full and stay feeling full (unlike quick-burning carbohydrates), and that also can help you maintain weight loss by keeping you from overeating. Proteins also help to build and maintain muscle mass, which can make exercise easier and more enjoyable, especially as you get older. That exercise is almost as important as calorie count in maintaining weight loss.

Not all proteins are equal, however. It's important to consume healthier proteins from leaner animal-based meats and plant-based sources to optimize protein benefits for weight loss.

Protein-rich foods

Ditching the low-carb, low-fat diet and adopting a healthy nutrient lifestyle is easier if you like what you're eating. Here are some good protein sources with high-quality nutrients to add to your plate:

• Eggs:

  One large, whole egg provides about 6 grams of protein, according to the USDA.

• Dairy products:

  Cottage cheese (11 grams per 100 gram serving) and Greek yogurt (9 grams) are excellent choices for a protein diet, as are cheddar (23 grams), swiss (27 grams) and mozzarella cheeses (23 grams).

• Nuts:

  Almonds (21 grams), pistachios and cashews are packed with protein and other macronutrients. Pumpkin seeds also make the list.

• Lean meats:

  Chicken, lean beef and fish all provide quality animal proteins and amino acids.

• Plant-based foods:

  Lentils, quinoa and soy are all good sources of plant-based protein, making them a good choice for those following a vegetarian or vegan diet or those wanting to cut down on animal products.

If you prefer low-protein foods, or you are concerned about how much protein you are getting from your diet, protein powder is an easy protein source, and it can be used in a variety of recipes—from smoothies and egg bites to baked goods. Soy-based protein and pea protein powders are available for those who avoid animal products.

Is maintaining weight easier than losing?

In many ways, weight loss is easier than trying to keep the pounds off. Many people achieve weight loss quickly by limiting their calorie intake and exercising, although this is not the case for everyone. Some factors, such as genetics and thyroid function, are out of your control and may make it harder to lose weight. Your gut microbiome is also a factor.

The problem is how quickly the weight seems to come back as soon as you stop your fat-free or carbohydrate-free diet and resume the calories (or carbohydrates, or fat, or sugars) that you ate before your weight loss. Research shows that most people regain weight after dieting. This makes sustained weight loss much harder than the initial weight drop. Sustained loss generally requires a complete overhaul of lifestyle.

This doesn't mean hopping from diet to diet; it means changing your entire eating pattern and relationship to food. Instead of banning foods from your life, with the hope that bread or bacon will simply stop being a temptation at your table, experts recommend adopting healthy eating lifestyles, such as the Mediterranean diet. Despite the name, the Mediterranean diet is more of an eating plan—it focuses less on restriction and more on choosing healthy foods.

5 tips for maintaining weight after a diet

1. Maintain a healthy diet.

   This does not mean be restrictive; it means moderation. Sustained weight loss often includes high-fiber, moderate- to high-protein foods, and lots of fruits and veggies.

2. Cut out low-nutrient, high-calorie foods and drinks that are easy to avoid.

   Soda is an obvious one that can be easily avoided for most people. But don't go overboard. You want your eating habits to last.

3. Get regular exercise.

   Exercise helps maintain muscle mass, energy levels, a healthy mood and more while it burns calories and helps contribute to your body weight goals.

4. Get enough sleep and manage your stress levels.

   Sleep is good for your physical and mental health in many ways, including weight. A national survey found significantly higher rates of obesity in adults who reported less than 7 hours of sleep a night, so getting good shut-eye may help weight loss.

5. Be realistic and be kind to yourself.

   Don't bite off more than you can chew when it comes to lifestyle. Many people start off intensely with their chosen eating and exercise plans, then it's too much to keep up with, so they drop it altogether. Don't do that! Be realistic. Don't try to completely eliminate foods that you know you'll want. Go for moderation, not perfection.

References

• Carbone, John W., et al. "Dietary Protein and Muscle Mass: Translating Science to Application and Health Benefit." Nutrients. May 2019. https://pubmed.ncbi.nlm.nih.gov/31121843/
• Lennon, Annie. "Weight loss: increased protein intake may prevent weight regain after a diet." MedicalNewsToday. December 2022. https://www.medicalnewstoday.com/articles/weight-loss-protein-may-prevent-weight-regain-after-diet
• Papatriantafylklou, Evangelina, et al. "Sleep Deprivation: Effects on Weight Loss and Weight Loss Maintenance." Nutrients. April 2022. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9031614/
• Van Baak, Marlene A., et al. "Dietary Strategies for Weight Loss Maintenance." Nutrients. August 2019. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6073115/
• Zhong, Wuling, et al. "High-protein diet prevents fat mass increase after dieting by counteracting Lactobacillus-enhanced lipid absorption." Nature Metabolism. December 2022. https://www.nature.com/articles/s42255-022-00687-6
• "Eggs, Grade A, Large, egg whole." FoodData Central, U.S. Department of Agriculture. https://fdc.nal.usda.gov/fdc-app.html#/food-details/748967/nutrients

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