Protein shakes are a convenient way to add more protein to your diet, but you need to keep a couple of things in mind. First: What's in your protein shake? Second: How does your protein shake fit in with your total daily calorie intake? Assuming that you plan your protein shakes so they're full of nutrition and balanced with the other foods you eat in a day, they shouldn't make you fat, even if you don't exercise.
If the calories in your protein shakes cause you to exceed your daily calorie needs, they will contribute to weight gain.
Weight Loss Explained
Many people who are trying to lose weight don't quite understand how weight gain, maintenance and loss happen — and for good reason. Body composition is a complicated concept that depends on a variety of factors, including, among other things, your age, gender, genetics and health status. But the one overriding factor is calorie intake.
To maintain your weight, you have to balance the calories you take in with the calories you use. All the calories you eat — whether they come from protein, carbohydrates or fats — are converted to fats in your body if they're not needed as an immediate source of energy. Your body stores that fat in case of a future shortage of energy, which is what causes weight gain.
Continuing to eat more calories than you need each day to support physiological function, daily activities of living and exercise will add to your body's fat stores. However, if you keep your calories balanced with your calorie output, you won't gain the fat.
Daily Calorie Needs
To avoid weight gain from protein shakes, you need to figure out your daily energy budget and make sure you can afford the calories in your shake. Without metabolic testing and a nutritionist, it's difficult to get an exact number, but you can get a good idea by using your age, sex and activity level as guides.
According to the Dietary Guidelines for Americans, a moderately active 35-year-old woman needs 2,000 calories per day, and a moderately active 35-year-old man needs 2,600 calories per day to maintain body weight. This is based on exercise equal to walking 1.5 to 3 miles each day at a moderate pace, in addition to performing the daily activities of living.
If you get no exercise at all and your only activities are your daily activities of living, you need fewer calories — 2,400 and 1,800 per day for a 35-year-old man and woman, respectively.
Calories From Protein
After you figure out your calorie needs, you can then determine how many calories should come from protein. According to the National Academy of Medicine, women need 46 grams per day and men need 56 grams per day. Another common estimate that's more specific to a person's weight is 8 grams of protein per kilogram of body weight. That's about 54 grams for a 150-pound person.
Since protein has 4 calories per gram, 54 grams of protein is 216 calories from protein each day. The rest of your calories will come from carbohydrates, which also have 4 calories per gram, and fats, which have 9 calories per gram.
Potential Problems With Protein Shakes
Protein powder without exercise needs to fit into your calorie and protein needs for the day, and it needs to contain nutritious ingredients. The problem is that many protein shakes don't meet these criteria.
All too often, protein shakes turn into milkshakes with sweet, calorie-rich ingredients like dried fruit, sweetened plant milks and nut butters with sugar added. These ingredients quickly pack on the calories, especially when you just throw things in the blender without measuring, as many people do.
Pre-formulated protein shakes are often even worse. In order to make them taste good, manufacturers add sugar and other nonnutritive ingredients. Don't just assume a protein shake is healthy or low in calories — read the labels to be sure you're not getting a dessert instead of a nutrition-boosting shake. Fewer than 3 grams of sugar per serving is ideal.
Protein Shakes and Your Diet
If you don't work out, it's unlikely that you won't be able to get the protein you need from three balanced meals each day. A 3-ounce chicken breast has 25 grams of protein, two large eggs have 12.5 grams of protein and 6 ounces of tofu have 12 grams of protein. Even a cup of cooked broccoli has almost 4 grams of protein.
The only time protein powder without exercise really makes sense is in a shake consumed in place of a meal. For example, a protein shake makes a nutritious breakfast on the go, especially when your other choices are less-healthy sugary cereals and baked goods — or no breakfast at all.
Replacing one meal a day with a low-calorie protein shake could help you reduce your daily calories to lose weight, even without exercise.
Examples of Healthy Protein Shakes
A healthy protein shake starts with a high-quality protein source. Whey, pea, hemp, brown rice and soy are all popular and readily available at your supermarket. Check the ingredients label to make sure it's either 100 percent protein or protein combined with other healthful, whole food ingredients. Avoid powders with ingredients like added sugar, fructose, syrups and fruit juice concentrate.
Add low-sugar, high-fiber and antioxidant-rich fruits, such as strawberries and blackberries. Throw in a handful of spinach. Choose a type of nut butter that has no added sugar and either cow's milk or plant milks that are also free of added sugar.
Nutritious additions such as flaxseeds or chia boost the fiber and nutrient content of your protein shake. You can also add superfoods such as raw cacao powder and matcha green tea. If you need a little sweetness, add half a banana or a small amount of stevia, a natural calorie-free sweetener from the stevia plant.
Measure out the ingredients when preparing your protein shake rather than tossing them in casually. A serving of berries is 1/2 cup; one serving of nut butter is 2 tablespoons; a serving of milk is 1 cup; and a serving of chia seeds is 1 tablespoon. Be sure that the total calories of your shake are not more than you would eat in a meal.
For example, if your calorie needs are 1,800 per day and you eat three 600-calorie meals, your shake should not contain more than 600 calories. If you eat a smaller breakfast of 400 calories and a larger lunch and dinner of 700 calories each, your breakfast shake shouldn't surpass the 400-calorie mark.
- Cleveland Clinic: Fat and Calories
- Dietary Guidelines for Americans: Appendix 2. Estimated Calorie Needs per Day, by Age, Sex, and Physical Activity Level
- National Academy of Medicine: Dietary Reference Intakes: Macronutrients
- USDA National Nutrient Database: Basic Report: Chicken, Broilers or Fryers, Meat Only, Cooked, Roasted
- USDA National Nutrient Database: Basic Report: Egg, Whole, Raw, Fresh
- USDA National Nutrient Database: Basic Report: MORI-NU, Tofu, Silken, Firm
- USDA National Nutrient Database: Basic Report: Broccoli, Cooked, Boiled, Drained, Without Salt
- UC Berkeley: Cal Dining: Serving Size Guide