If more protein is consumed than is needed, the body breaks the protein down and stores its components as fat. The body contains large amounts of protein. Protein, the main building block in the body, is the primary component of most cells. For example, muscle, connective tissues, and skin are all built of protein.

Adults need to eat about 60 grams of protein per day 0. Adults who are trying to build muscle need slightly more. Children also need more because they are growing. People who are limiting calories to lose weight typically need a higher amount of protein to prevent loss of muscle while they are losing weight.

Fats are complex molecules composed of fatty acids and glycerol. The body needs fats for growth and energy. Fats are the slowest source of energy but the most energy-efficient form of food. Each gram of fat supplies the body with about 9 calories, more than twice that supplied by proteins or carbohydrates. Because fats are such an efficient form of energy, the body stores any excess energy as fat. The body deposits excess fat in the abdomen omental fat and under the skin subcutaneous fat to use when it needs more energy.

The body may also deposit excess fat in blood vessels and within organs, where it can block blood flow and damage organs, often causing serious disorders. When the body needs fatty acids, it can make synthesize certain ones. Others, called essential fatty acids, cannot be synthesized and must be consumed in the diet.

They include linoleic acid and linolenic acid, which are present in certain vegetable oils. Eicosapentaenoic acid and docosahexaenoic acid, which are fatty acids essential for brain development, can be synthesized from linolenic acid.

However, they also are present in certain marine fish oils, which are a more efficient source. Linoleic acid and arachidonic acid are omega-6 fatty acids. Linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid are omega-3 fatty acids. A diet rich in omega-3 fatty acids may reduce the risk of atherosclerosis Atherosclerosis Atherosclerosis is a condition in which patchy deposits of fatty material atheromas or atherosclerotic plaques develop in the walls of medium-sized and large arteries, leading to reduced or The heart muscle needs a constant supply of oxygen-rich blood.

The coronary Lake trout and certain deep-sea fish contain large amounts of omega-3 fatty acids. In the United States, people tend to consume enough omega-6 fatty acids, which occur in the oils used in many processed foods, but not enough omega-3 fatty acids.

Women who are pregnant or breastfeeding should choose fish that are low in mercury. See Mercury in Seafood Mercury in seafood Some risk factors are present before women become pregnant. These risk factors include Certain physical characteristics, such as age, and social characteristics of women Problems in a previous Saturated fats are more likely to increase cholesterol levels and increase the risk of atherosclerosis Atherosclerosis Atherosclerosis is a condition in which patchy deposits of fatty material atheromas or atherosclerotic plaques develop in the walls of medium-sized and large arteries, leading to reduced or Foods derived from animals commonly contain saturated fats, which tend to be solid at room temperature.

Fats derived from plants commonly contain monounsaturated or polyunsaturated fatty acids, which tend to be liquid at room temperature. Palm and coconut oil are exceptions. They contain more saturated fats than other plant oils. Trans fats trans fatty acids are a different category of fat. J Am Heart Assoc. Erythrocyte omega-3 fatty acids increase and linoleic acid decreases with age: observations from , patients.

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What makes omega-3 fats special? They are an integral part of cell membranes throughout the body and affect the function of the cell receptors in these membranes. They provide the starting point for making hormones that regulate blood clotting, contraction and relaxation of artery walls, and inflammation.

They also bind to receptors in cells that regulate genetic function. Likely due to these effects, omega-3 fats have been shown to help prevent heart disease and stroke, may help control lupus, eczema, and rheumatoid arthritis, and may play protective roles in cancer and other conditions.

The strongest evidence for a beneficial effect of omega-3 fats has to do with heart disease. These fats appear to help the heart beat at a steady clip and not veer into a dangerous or potentially fatal erratic rhythm. Omega-3 fats also lower blood pressure and heart rate, improve blood vessel function, and, at higher doses, lower triglycerides and may ease inflammation, which plays a role in the development of atherosclerosis. Several large trials have evaluated the effect of fish or fish oils on heart disease.

In the more recent Japan EPA Lipid Intervention Study JELIS , participants who took EPA plus a cholesterol-lowering statin were less likely to have a major coronary event sudden cardiac death, fatal or nonfatal heart attack, unstable angina, or a procedure to open or bypass a narrowed or blocked coronary artery than those who took a statin alone. Most Americans take in far more of another essential fat—omega-6 fats—than they do omega-3 fats. Some experts have raised the hypothesis that this higher intake of omega-6 fats could pose problems, cardiovascular and otherwise, but this has not been supported by evidence in humans.

Omega-3 and omega-6 fatty acids are precursors to important compounds called eicosanoids. Eicosanoids are powerful hormones that control many other hormones and important body functions, such as the central nervous system and the immune system. Eicosanoids derived from omega-6 fatty acids are known to increase blood pressure, immune response, and inflammation. In contrast, eicosanoids derived from omega-3 fatty acids are known to have heart-healthy effects.

Given the contrasting effects of the omega-3 and omega-6 fatty acids, a proper dietary balance between the two must be achieved to ensure optimal health benefits.

Essential fatty acids play an important role in the life and death of cardiac cells, immune system function, and blood pressure regulation. Docosahexaenoic acid DHA is an omega-3 essential fatty acid shown to play important roles in synaptic transmission in the brain during fetal development. Some excellent sources of omega-3 and omega-6 essential fatty acids are fish, flaxseed oil, hemp, walnuts, and leafy vegetables.

Because these essential fatty acids are easily accessible, essential fatty acid deficiency is extremely rare. Like triglycerides, phospholipids have a glycerol backbone. But unlike triglycerides, phospholipids are diglycerides two fatty-acid molecules attached to the glycerol backbone while their third fatty-acid chain has a phosphate group coupled with a nitrogen-containing group. This unique structure makes phospholipids water soluble.