You consume 3 macronutrients (macros) throughout your day: fat, carbohydrates (carbs), and protein. All 3 play essential roles in the body, but I'm here to argue that protein is perhaps the most important for maintaining a long health span. It's a critical nutritional constituent for strength, muscle mass, weight loss, and longevity. Unfortunately, it's also the most challenging macro to consume in optimal quantities. Let's talk about the benefits of consistent dietary protein intake and how it can prevent some of the most common causes of death and physical deterioration.
Let's start with a little background. Protein is made up of amino acids, unlike carbohydrates and fats which are made up of saccharides and fatty acids respectively (note, this is oversimplified). There are 20 common amino acids and 9 of them are deemed "essential", meaning that you cannot synthesize them yourself. Rather, you can only get them through your diet. These dietary amino acids are used as building blocks for new proteins in your body and they also play very important metabolic functions.
Protein is the primary structural component of your skeletal muscle, among many other biological structures in your body. Protein also has a relatively low caloric footprint. At 4 calories per gram, it's almost half as calorie dense as fat at 9 calories per gram. If you're curious, alcohol clocks in at 7 calories per gram. Although it's calorically equal to carbs (also 4 calories per gram), it has an important separator: thermic effect. Let's put on our nerd caps. The thermic effect is an estimation of the caloric cost of consuming different macronutrients. Even though there are more calories in macros than it costs to digest them (meaning you can't lose weight by eating more), protein may have up to 5 times the thermic effect of fat and carbs. This means if you eat 100 calories worth of protein, between 20-35 calories will be burned to digest them. Pretty cool. If you're curious, carbs have less of a thermic effect compared to protein, but more so than fat.
Perhaps the main benefit of protein is its effect on muscle protein synthesis (MPS), which is literally how your body builds muscle. Having a lot of muscle on your frame can be advantageous for multiple reasons. It increases strength, mobility, agility, and aesthetics, and it decreases the risk of falling, cardiovascular disease, diabetes, broken bones, and potentially even cognitive decline! All of these things are great, but they become essential as you age.
Let's take something as simple as falling down. Many people don't know that grip strength (as in the muscular strength in your hands, arms, and shoulders) is inversely related to your risk of falling. This is because as you age, when you trip and try to grab onto something like a rail, bedframe, or chair, you literally aren't strong enough to catch yourself. That's when you inevitably hit the ground and break a hip. Think about this, roughly 70% of accidental deaths in people > 75 years old are caused by falls. More than 90% of hip fractures are caused by falls. More than 33% of elderly people will fall each year and 60% of nursing home patients suffer a fall annually. Perhaps most concerning, roughly 12-33% of people who fracture their hip will die within a year.
Of course, the risk of falling is not only associated with decreased strength and muscle mass, but also with dementia and cognitive decline. However, you've likely noticed that cognitive decline and decreased strength run hand in hand. Very rarely will you see a patient with severe dementia that is also able to do a pull-up or bodyweight squat. It's possible there's actually a causal link between low skeletal muscle mass and cognitive decline. There's also the factor of bone density, which is especially a concern in women (75% of hip fractures occur in women). Young men and women can effectively increase their bone density by increasing skeletal muscle strength with regular exercise. Most people's bone density will peak in their 30s and then steadily decline. The higher your peak, the more decline you can afford without consequence. Not to mention, the rate of decline can also be diminished with regular exercise.
Then we have good ole diabetes. A terrible disease but largely a preventable one. Here again, increased skeletal muscle can be a saving grace. Diabetes is a problem of insulin insensitivity and lack of glucose regulation leading to hyperglycemia (too much sugar in your blood). Luckily, skeletal muscle is a great depot for glucose and is eager to remove it from the bloodstream via GLUT-4 receptors on muscle cells. So, especially as we age, regular exercise and protein consumption can effectively decrease your risk of diabetes. It's imperative that you take a preventative approach here! Otherwise, you risk the exact opposite outcome, diabetic muscle infarction which is the spontaneous death of skeletal muscle (not good).
Long story short, if we want to optimize our health and longevity, we have to optimize skeletal muscle. In order to do that, we must focus on being consistently active and prioritize protein in our diets to take advantage of MPS. We will explore the best protein sources, how much protein you need per day, and much more about diet, exercise, skeletal muscle, and longevity in future posts. Feel free to share your favorite protein sources and exercises in the comments below!