There are three categories of macronutrients: protein, carbohydrates, and fats. Each is important to include in a well-rounded diet, but the question is, how much and what types of each should we have, and why? Find out below! 

Protein

There are two different sources of protein to consider. Animals and plants can provide the protein needed in your diet. When we consume protein, it is broken down into amino acids to be used in the body. While our bodies can produce some amino acids, those referred to as non-essential amino acids, the amino acids come from food sources are called essential amino acids. The major difference between animal and plant protein sources is that animal sources are complete and plant sources are not. To be a complete protein source, all essential amino acids must be present. 

There are benefits and detriments to each source. For example, red meat is a good source of protein, but has a bad rap for causing health problems. Research shows while processed red meat is the source of a number of health issues, not all red meat is bad for you. Consuming red meat that is grass-fed, and preferably "grass finished", will ensure you are receiving high-quality protein without the risks. 

Overall, plant-based diets have been linked to many health benefits. Vegetarians tend to weigh less, have lower blood pressure and have lower cholesterol. They also have lower disease risk. People who eat plant-based diets have lower risk of:

• Stroke
• Cancer
• Heart disease
• Type 2 diabetes
• Weight gain

However, plant sources of protein are missing some essential amino acids and nutrients. The key to getting all you need from your vegetarian or vegan diet is to include a variety of foods. However, it still may require supplementation of essential amino acids and micronutrients for optimal health. We require amino acids to build proteins and perform other functions within the body.

Amino acids are necessary for:

• Muscles 
• Hormones 
• Enzymes 
• Structure (Collagen) 
• Proper pH 
• Fluid Balance 
• Immune Health 
• Transportation and storage of nutrients 
• Can be used for energy (4 kcal per gram) 

Requirements

Varying amounts of protein are necessary in your diet, depending on your activity level. For the person who does minimal activity, i.e. one that does not participate in exercise, consuming 8 grams of protein per kilogram of bodyweight (one kilogram is approximately 2.2 lbs) is the general recommendation. Those that exercise 3-5 times a week at a moderate to vigorous intensity require 1.2 grams to 1.7 grams of protein per kilogram of bodyweight. Elite athletes can tolerate much more protein intake at 3.5 grams per kilogram of bodyweight. A person that weighs 70 kilograms (approximately 154 lbs) would need 56 grams of protein if participating in minimal activity, 84-119 grams if regularly exercising, and 245 grams if an elite athlete. A single gram of protein is converted to 4 kcal or calories, meaning a 70 kg (154 lb) person could be consuming anywhere from 224 to 980 calories from protein-based sources. 

Servings

Now that you know your individual daily protein requirements, what's next? One of the most difficult parts of translating scientific information on protein requirements into action in your everyday life is determining serving sizes and how to incorporate the correct amount of protein into the meals you consume each day. Below are some examples of great sources of protein, serving sizes, and the grams of protein in each. 

Carbohydrates 

In recent years carbohydrates (carbs) have been portrayed as "bad" and as a cause of us being overweight. However, carbs are actually important macronutrients and are vital to our survival. In fact, our brains prefer carbs as an energy source over protein and fat. Readily converted into glucose, carbs are the most easily accessed source of energy for the body and a single gram of carbohydrate produces 4 calories of energy. 

The negative issue with carbs is eating poor quality or too many of them. Our supermarkets and grocery stores are filled with processed foods chocked full of carbs because they are cheap and tasty. If you choose the carbohydrates in your diet carefully, they will contribute to your health instead of taking away from it. Fruits, vegetables, and unprocessed grains and legumes provide the highest quality nutrients. While white bread, french fries, and sugary cereal are examples of low quality carbohydrates to avoid. 

Fiber is also a type of carbohydrate that is important to our health. We cannot digest fiber, but there are still many health benefits. Fiber helps with digestion, blood sugar control, lowering cholesterol, and disease prevention. 

Requirements

The amount of carbohydrates you need each day depends on the total amount of calories you eat in a day. The general recommendation is that 45 to 60% of your calories should come from a carbohydrate source. Some diets may have lower percentages of carbs, but if you choose to do that, communicate with your health care provider prior to starting. 

Servings

Eating the appropriate amount of carbohydrates can be a struggle when it is difficult to understand serving size and how that relates to carbohydrate content and total calories consumed. Below are some examples to guide you in your food choices and creation of your diet plan. 

Fats 

Including fat in a healthy diet may seem counterintuitive, but fat actually plays a pivotal role in everyday function and living our healthiest lives. 

Purposes of Fat:

• Storing fat-soluble vitamins 
• Can be used for energy
• Protect organs 
• Keep you warm 
• Produce hormones 
• Satiety signal

The key to including fat in our diets is the choice of the fats. Choosing unsaturated fats over trans fats and saturated fats will ensure you receive the necessary nutrients without the detrimental effects. Saturated and trans fats can increase LDL (bad) cholesterol and decrease HDL (good) cholesterol. LDL cholesterol takes fat from the liver and distributes it into the bloodstream where it could cause blockages or other issues. HDL cholesterol takes fat from the bloodstream and brings it to the liver for processing and removal.

This of course does not mean you should eat as much unsaturated fat as you can get your hands on. Fat provides 9 calories per gram eaten, more than double the number of calories per gram of carbohydrate and protein. The amount of fat in your diet needs to be monitored, whether it's healthy fat or not, so you can meet your calorie goals for the day. 

Requirements

The general recommendation for fats to include in your diet is 35 to 40% of the calories you eat in a day. There are a few diets that increase or decrease this recommendation based on the purpose and goals of the diet. In a low-fat diet, less than 30% of your daily calories should be from fat, while in a high-fat or ketogenic diet, about 70% of your calories should come from fat. 

Servings  

Once you know the grams and calories of protein and the grams and calories of carbohydrates you should consume in a day, it is then easy to figure out the grams and calories that should come from fat. The fat you should consume is whatever is leftover in your calorie equation. 

Sources: 

• https://www.healthline.com/nutrition/functions-of-protein 
• https://www.healthline.com/health/heart-disease/good-fats-vs-bad-fats 
• https://www.healthline.com/nutrition/how-much-fat-to-eat 
• https://www.healthline.com/health/too-much-protein#risks 
• https://www.medicalnewstoday.com/articles/318617 
• https://www.health.harvard.edu/mens-health/carbohydrates-in-your-diet-its-the-quality-that-counts
• https://www.hsph.harvard.edu/nutritionsource/carbohydrates/fiber/
• https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-and-cholesterol/types-of-fat/