What diet is most effective? How much exercise is recommended? Is exercise or diet more effective?
Providing an answer to each of these questions requires the understanding of metabolism. Metabolism is how efficiently the body utilizes ingested fuel. It is composed of the resting metabolic rate, physical activity, and diet induced thermogenesis. The resting metabolic rate is 65% of the metabolism. It is genetically based and determines the hypothalamic set point. The more fat free mass, the higher the metabolism. For example, the liver, heart, brain, and kidney contribute up to 75% of the resting metabolism with adipose or fat tissue only contributing 5%. Physical activity comprises approximately 20-45% of the metabolism. The diet induced thermogenesis, or the energy necessary in nutrient consumption, comprises 10-15%. Thus, metabolism manipulation results from alterations in one of these three components. However, it is significant to understand the equation for weight management is simply in=out, maintenance, in>out, weight gain, and in<out, weight loss.
Manipulating the resting metabolic rate is difficult. This rate is pre-determined by the body. It is the point the body desires to maintain. When complying to a diet plan such as a calorie reduction of 250-500 calories per day, the body allows loss for a temporary time, but soon plateaus. For example, upon a 10% weight reduction, a 6% energy output reduction occurs. This design is a protective factor, challenging the long term weight loss. In accomplishing an enhanced metabolism by altering the resting metabolism requires exercise and conditioning to the point of long lasting adaptions.
These adaptions result from both cardiovascular and resistant training, including neuronal, muscular, cardiovascular, connective, and immune alterations. Neuromuscular adaptations entail enhanced motor unit recruitment, activity, and firing rate resulting in greater muscular force and power. Muscle adaptations entail increased muscle cross sectional area, increased muscle cell number, and decreased muscle damage with repeated exposure. Cardiovascular adaptations entail improved cardiac output, stroke volume, oxygen carrying capacity, diffusion capacity or oxygen and carbon dioxide exchange, and capillary and mitochondria hyperplasia. Connective changes are demonstrated as elevated bone mineral density and collagen synthesis, causing increased strength and force. Immunity improves secondary to leukocyte and cytokine responses, resulting in tissue repair. Overall, from a human perspective, enhanced muscle power, strength, endurance, performance, balance and coordination along with decreased body fat, increased insulin sensitivity, and increased basal metabolic rate results.
Exercise improvements, however, are only part of the equation. Diet is significant in sustaining the metabolism and activity level. This plays an essential role in the thermogenetic effect, too. Food is fuel. It is imperative to nourish the body with the macro and micro nutrients it is composed of. Thus, carbohydrates, proteins, fats, and water are essential. Carbohydrates are the preferred source of energy. Carbohydrates are utilized first. They are significant in high intense and short exercise bursts. However, once the exercise continues and intensity reduces, the main source of fuel is fats. Fats are burned slowly and produce more energy as compared to carbohydrates. Proteins are only used in a last resort. Proteins are preferred for repair and restoration. In addition, water is required for life. Just a 2% dehydration level can affect functioning and reduce the metabolism. Therefore, diet behavior plays a role in increasing metabolism as well. The behavior entails drinking approximately 1-2 liters of water per day, eating a variety of complex carbohydrates, including fruits and vegetables and those with > 3 grams per serving of fiber, reducing saturated fat to < 7% with a consumption of 15-25% of monounsaturated fats defined as fish, nuts, flaxseed, olive oil, and consuming 0.5-1 gram per kilogram of lean sources of protein such as eggs, chicken, turkey, and fish. By adhering to these behaviors, the metabolism can be increased. In fact, many of these fuel sources are considered free foods, meaning it requires more energy to metabolize than the food itself provides. As a result, the thermogenic effect enhances.
In conclusion, metabolism is difficult to manipulate. However, diet and exercise, contribute to long lasting adaptations and improved quality of life. Master that metabolism.
Pharm D, BCPS, BCACP, CDE, MSMTM, BSN, CPTT