There is plentiful evidence that eating more protein can help you feel satisfied on fewer calories when you're trying to lose weight. And when your daily limit is a slim 1,200 calories, you need all the help you can get. When upping your protein, just remember to choose lean, low-calorie sources.
How Low Can You Go?
Twelve hundred calories a day is a very low calorie intake. According to the National Institutes of Health, 1,200 calories is suitable for many women who want to lose weight, depending on their activity level; however, it is too few for most men, who require more calories than women. So before you dig into designing your high-protein plan, just make sure you're not setting your sights too low.
Video of the Day
While reducing your calories is key for weight loss, eating too few calories — no matter whether they come from protein, carbs or fat — can potentially hinder weight loss. Not only will you frequently feel hungry, but your metabolism may actually slow down as your body adapts, metabolically, to functioning on significantly less energy. If you exercise regularly, you may further put yourself at risk of health problems due to too few calories.
High-Protein Diets Boost Satiety
With or without calorie restriction, protein has several effects on appetite and metabolism that can be a boon to slimming down. The first of these is satiety, or the feeling of fullness and satisfaction you feel after eating a particular food. According to an article in the February 2015 issue of Trends in Food Science & Technology, protein is the most satiating nutrient, followed by carbohydrate, then fat.
Protein ingestion stimulates the production of several hormones that affect satiation signaling, or sending signals to the brain that the body has had enough to eat, according to an article published in November 2014 in Nutrition & Metabolism. Among these are the incretin hormones, which are synthesized in the gut and secreted by the endocrine system, and cholecystokinin (CCK), another hormone found in the gastrointestinal tract and the brain.
One incretin hormone in particular, called glucagon-like peptide-1 (GLP-1), appears to activate central nervous system nuclei that are involved in satiation, reports the author of a research review published in September 2013 in the International Journal of Obesity. CCK is responsible for slowing stomach emptying, which creates a longer-lasting feeling of fullness.
Increasing Metabolism and Preserving Muscle
In addition, protein can temporarily boost metabolism. Protein is more difficult for the body to digest than carbohydrate, therefore the body has to expend more energy. This results in a temporary rise in metabolic rate during protein digestion and a lower net energy intake. According to the 2014 Nutrition & Metabolism review, protein metabolism increases base metabolic rate by 15 to 30 percent. For carbs, the potential increase is 5 to 10 percent, and for fat it's just 0 to 3 percent.
Lastly, eating more protein when you're on a low-calorie diet can help you preserve muscle mass. The body doesn't preferentially burn fat just because you reduce your calorie intake. In fact in the beginning of a diet, your body may burn lean muscle mass for energy, in addition to stored carbohydrate and a smaller amount of fat, according to an article in the Journal of the Academy of Nutrition and Dietetics in June 2014.
Preserving muscle mass is crucial for weight loss because muscle is more metabolically active than fat — as much as four times more active, report Paige Kinucan and Len Kravitz, PhD, of the University of New Mexico. Having more muscle mass means you burn more calories round the clock, even when you're not doing anything.
How Much Protein?
The recommended dietary intake for protein for the general population determined by the Food and Nutrition Board of the National Academies of Medicine is 46 grams for women and 56 grams for men each day. Since protein has 4 calories per gram that works out to 184 or 224 calories from protein (although, as mentioned above, such a low calorie intake isn't appropriate for most men.) That's roughly 15 to 18 percent of your calorie intake on a 1,200-calorie diet.
You can also figure out your protein needs based on how much you weigh. The Food and Nutrition Board bases its recommendation on about 0.8 grams of protein per kilogram of the average person's body weight. So, for example, if you weigh 150 pounds, you would need 55 grams of protein. But if you weigh 190 pounds, you would need to aim for close to 70 grams of protein.
But you might choose to go higher than that. In a study published in Obesity Facts in June 2017, participants followed either a standard protein diet or a high-protein diet. Those who adhered to the high-protein diet had lost significantly more weight at the end of the six-month trial.
The standard-protein group consumed the established 0.8 grams per kilogram of body weight, while the high-protein group consumed 1.34 grams per kilogram. That would mean 91 grams of protein for a 150-pound person and 115 grams for a 190-pound person each day.
Choosing the Best Protein Sources
Making this work means fitting your target protein goals into your daily calorie landscape. If you're shooting for 90 grams of protein, remember that with 4 calories per gram, according to the USDA, that's 360 calories, or more than a fourth of your budget. If you're going even higher, you could be spending nearly 50 percent of your calories on protein.
Now comes the hard part — figuring out how to stretch your budget so you get the most bang for your calorie buck. Sure, you could eat a fast food hamburger and get about 15 grams of protein; but you'd have to spend more than 250 calories, according to USDA data. However, if you made a healthier choice, such as a grilled chicken breast (3 ounces) without skin, you'd get about 27 grams of protein for only 142 calories.
Or, maybe you prefer fish or tofu? Either way, these are lean sources of protein that are packed full of health-promoting nutrients and low in calories. Other healthy choices include eggs, beans and low-fat dairy. Lean red meat is OK in small amounts infrequently; however it's crucial to avoid fatty cuts of meat and processed meats.
In addition to lean sources of protein, you also need adequate carbohydrates for energy and healthy fats for heart health. Non-starchy vegetables like leafy greens, bell peppers and broccoli are nutrient rich and low in calories, and whole grains provide essential vitamins and minerals. Both provide dietary fiber, an indigestible part of plant food that aids digestion and, like protein, can also help increase satiety.
There's no wiggle room on a 1,200-calorie diet. Candy, cookies, soda, baked goods, fried and fast foods, and desserts offer no nutrition, no satiety and lots of calories. When you feel a junk food craving coming on, reach for a protein-rich snack to help you feel full and happy.
- National Institutes of Health: "Healthy Eating Plan"
- Journal of the International Society of Sports Nutrition: "Metabolic Adaptation to Weight Loss: Implications for the Athlete"
- Trends in Food Science & Technology: "Optimising Foods for Satiety"
- Nutrition & Metabolism: "A High-Protein Diet for Reducing Body Fat: Mechanisms and Possible Caveats"
- International Journal of Obesity: "Incretin Hormones and the Satiation Signal"
- Journal of the Academy of Nutrition and Dietetics: "Time to Correctly Predict the Amount of Weight Loss with Dieting"
- University of New Mexico: "Controversies in Metabolism"
- National Academies of Medicine: "Summary Tables, Dietary Reference Intakes"
- Obesity Facts: "Effect of a High-Protein Diet Versus Standard-Protein Diet on Weight Loss and Biomarkers of Metabolic Syndrome: A Randomized Clinical Trial"
- USDA: "Basic Report: 21250, Burger King, Hamburger"
- USDA: "Basic Report: 05064, Chicken, Broilers or Fryers, Breast, Meat Only, Cooked, Roasted"
- USDA: "How Many Calories Are in One Gram of Fat, Carbohydrate, or Protein?"