Protein is a nutrient essential for maintaining your muscle mass, keeping your immune system strong and allowing vital reactions to occur in your body. Most American adults get more protein than necessary, but you may have reason to focus on your intake if you need to gain weight or if you are a hard-training athlete.

Even under healthy conditions, too much of any macronutrient can cause digestive discomfort. While eating too much protein poses little risk of damaging your stomach or any digestive organs if you are otherwise in good health, you may experience gastrointestinal pain if you overindulge in protein.

Amino acids are the building blocks of protein, which your body uses to make new tissues and repair damaged tissues, and protein-rich foods like fish, poultry and beef are some of the best sources. The amino acid profiles of animal foods vary, with some being higher in certain amino acids than others.

Garlic has a long history of use as a food and medicine. From topical garlic preparations that helped prevent war-wound infections, to its us as an antibiotic during World War II when Russian soldiers ran out of penicillin.

When you cook a protein-rich food like an egg, you'll change the structure of the protein, but your body will still be able to use the amino acids to build and repair cellular tissue and synthesize protein-based compounds. Scrambled eggs are a good source of protein.

Whey and chicken both serve as a protein source in your diet. While they share similarities, they offer important differences in terms of nutrition, preparation, digestion and absorption.

Caffeine, one of the most popular stimulants in the world, is present in coffee, tea, chocolate, energy drinks and some colas. Caffeine stimulates the central nervous system and decreases fatigue by interfering with a chemical in the body that promotes sleepiness.

You might take protein shakes after exercise to boost muscle building. If you are underweight, protein shakes can also help you gain healthy weight. Homemade shakes usually contain protein powder, fruit or nut butter and milk. The type of milk you use depends on your goals and health needs.

Whey contains all of the essential amino acids, or EAAs, your body needs but cannot produce itself. There are nine EAAs and each has its own function in the body. It’s important to get enough EAAs each day, especially when trying to build and maintain lean muscle mass.

Magnesium supports a healthy immune system, keeps bones strong, regulates blood sugar, maintains muscle functions and nerves. While your body depends on getting enough magnesium to function properly, getting too much of this mineral has numerous side effects. One of these side effects is an upset stomach.

As you age, the approximate proportions of different macronutrients your need stays the same but your total caloric needs decrease. Men between 51 and 70 need 2204 calories per day and after 70 need 2054 calories a day. Women's caloric needs decrease from 1978 calories a day from 51 to 70 to 1873 after 70.

Carbohydrates, protein and lipids are macronutrients that provide the body with calories. Nutrients are required for proper growth, metabolism and most body functions. While both macro and micronutrients are important for good health, macronutrients are necessary in large amounts.