One of the main building blocks of life is protein. Not only does this macronutrient make up a major component of all of our cells, it also gives us the essential amino acids that keep our bodies functioning. But there is a problem: a majority of us are not eating as much protein as we should be. Here are some signs that you may not be getting enough protein in your diet.

1. Do you get stress fractures often? It takes more than just calcium to keep your bones healthy. They need to have enough protein, too. With a diet rich in protein, you can actually help protect your bones. If your body isn’t getting enough protein to actually fuel itself, it will borrow it from other areas, which includes raiding skeletal storage. If you do not have strong skeletal muscle tissue, then your bones will be more prone to breaking or fracturing.

2. Do your hair and nails look brittle? Protein is an essential part of healthy hair and nails. Over time, without adequate protein, your hair can become brittle and your nails can get softer. If your protein intake stays low, you will even begin to see some hair loss. This is because your body will shut down hair growth in order to preserve its protein stores.

3. Are you losing weight but feeling weaker? You may get excited because you see the numbers on the scale going down, but that can also be a bad thing. When your body doesn’t get the protein it needs, it will start to take that protein away from your muscles. If you are losing muscle, this can mean that your body is holding on to fat stores, which is the opposite of what you want your body to do.

4. Are you feeling weaker? If you are not feeding your body enough protein, you can start to feel more tired or sluggish than normal. The key to this is muscle mass. Our muscle mass contributes to hemoglobin, which shows up in our blood cells. Hemoglobin transports oxygen throughout the whole body. If you do not have enough of it, then your body will not get the amount of oxygen it needs, which can lead to feeling weak and experiencing shortness of breath.

5. Do you feel like you always have a cold? Believe it or not, we need protein to build up our antibodies. Antibodies are actually produced by the immune system and help us to keep out or fight off bacteria. However, if you do not have enough protein in your diet, you could be setting your immune system up for failure instead of success, which will most likely lead to you spending more time feeling sick.