Our bodies need protein for pretty much everything. It’s the building block of all the cells in our bodies—skin, muscles, bones, cartilage, hair, you name it. Eating enough of it every day is essential for our bodies to repair damaged cells and to create new ones. When you get too little protein, over time, it can impact every aspect of your health.
Most people get the protein they need most of the time, and full blown protein deficiency is uncommon in the U.S. and other developed countries. But if you’re sticking to a regimented diet, it’s possible you’re not giving your body the protein it needs, which can lead to food cravings, impede your fitness goals, or have other wide-ranging effects on how you look and feel.
The amount of protein each of us needs varies depending on our age, sex, height, weight, and activity levels. As a general recommendation, the USDA suggests 0.8 grams of protein per kilogram of body weight (divide your weight in pounds by 2.2, then multiply by 0.8). “Most young adults who consume a widely varied diet will easily meet their protein requirements on a daily basis,” Dana Hunnes, Ph.D., M.P.H., R.D., senior dietician at UCLA Medical Center and adjunct assistant professor at the Fielding School of Public Health, tells SELF. But, she adds, “calorie-restrictive diets sometimes can lead to decreased protein intake.”
The people most likely to be low in protein are those who are chronically ill or who undereat, Alissa Rumsey, M.S., R.D., spokesperson for the Academy of Nutrition and Dietetics, tells SELF. “Some vegans and vegetarians are at risk if they aren’t including enough plant-based protein in their meals,” she adds. (There are plenty of plant-based proteins to choose from, though, if you don’t eat meat—here are some great options.)
Here are some signs you might not be getting enough of this important macronutrient.
1. You crave protein.
If you’re not eating enough protein, in the short term, your body may tell you by craving it, Hunnes says. You should give into these cravings. If you’re really jonesing for a chicken sandwich or a bowl of lentil soup, listen to your body and eat up.
2. You crave sugar.
“Protein (along with fat) digests slower than carbohydrates. If you eat a meal that is mostly carbohydrates, with not enough protein, it will digest more quickly and will cause your blood sugar to rise,” Rumsey says. This rise is followed by a drop—and when blood sugar is constantly spiking and dropping, we crave more sugar. The key is to eat protein with carbs so that everything digests more slowly, and the blood sugar changes are more gradual over time.
3. Your hair is thinning.
Hair is made up of mostly protein (keratin, specifically). If you’re consistently not getting enough protein, over time, you may notice your hair start to thin or even fall out. That’s because your body stops using protein for non-essential things like hair growth in an effort to preserve its stores.
4. Your nails and skin are weak.
Protein is also essential for nail and skin cells to grow. If you’re not getting enough of it, eventually your nails may get weaker and your skin may get flaky, Rumsey says. Hunnes adds that protein deficiency may also cause rashes or other dermatologic problems.
5. You get sick often.
“Protein is needed to build the components of our immune system,” Rumsey explains. “If you are under-eating protein, over time your immune system may weaken.”
6. You feel tired or weak.
“For most people, eating too little protein over the course of one day will not make you feel less energy or strength, particularly if you are getting a sufficient number of calories in that day,” Hunnes says. But long term, your body may break down your muscles to try and supply your body with sufficient protein, leading to loss of energy and strength, she explains. Low energy and strength can also be impacted by overall diet quality, sleep, stress, and lack of physical activity, so if you’re feeling this way often, it’s important to check in on all of your lifestyle habits.