Protein is considered as one of “the building blocks of life” and rightly so. It provides our bodies with the crucial amino acids that keep our bodies running. The point of concern is that many of us are not getting as much protein our bodies need.

In the United States, true protein deficiency is rare but vegans or some other people who follow a raw food diet can be lacking this macronutrient observes, Leslie Bonci, MPH, a nutritionist, owner of Active Eating Advice, and nutrition consultant for the Kansas City Chiefs. A vegan diet cuts out all animal products including- meat, eggs, honey, fish, gelatin, and dairy- all of which are major sources of protein.

Here are five signs that you may not be getting as much protein as you should be.

You’re prone to stress fractures-Bones need protein in addition to calcium to be healthy. According to Bonci, when there isn’t enough protein in our body to fuel the organs the body borrows from other storages like the skeletal muscle tissue. If the skeletal muscle tissue is not strong enough the bones become more susceptible to fractures and injuries.

Your hair and nails look brittle-Protein is an important component of hair and nails and the nails and hair might become more brittle with time because of its deficiency. Bonci said, “The hair can lose some of its luster, and may not be quite as thick as it used to be. It may also start to split.”

If your body does not get enough protein for some months, you might even start losing hair. American Academy of Dermatology notes that this happens partly to preserve the protein stores for other parts, the body shuns the hair growth.

You’re losing weight—from your muscles-According to Bonci, “Typically, if people aren’t getting enough protein, their bodies will break down muscle to get more of it. And if they’re losing muscle, they’re also holding on to fat stores, so their body composition could be changing in an adverse way.” So losing weight is not necessarily a good sign.

You feel weak-Fatigue won’t show right away but over time, people who do not get enough protein may start feeling more tired than usual, according to Bonci. Hemoglobin in the red blood cells has protein as a component. Red blood cells are responsible for transporting oxygen throughout the body. Low levels of oxygen can cause weakness and in some cases shortness of breath.

You’re always catching a cold- According to Bonci, “If you don’t have enough protein, you could have a compromised immune system and perhaps be ill more often than other people.” Body’s immune system produces antibodies which fight alien invaders like viruses and protein is one of the building blocks of these.