Medications that Affect Nutrient Partitioning

The chemical action of some medications may have side effects of increasing or decreasing body weight. The body handles nutrients through nutrient partitioning by storing nutrients, using nutrients to convert food to chemical components, releasing the heat created from biochemical processes, or excreting. Energy taken into the body through foods and beverages must go through the digestion process. Carbohydrates provide the sugars that create energy in the body, proteins are broken down to individual amino acids for the building of muscle, fats are the primary long-term energy source and are stored largely unchanged in adipose tissue.

Nutrient partitioning can be affected by metabolic changes, blocking or inducing storage, and increasing or decreasing excretion. Medications may have unintentional side effects of increasing metabolism, stimulating the thyroid, or working directly in the digestive tract. Medications that can affect nutrient partitioning include corticosteroids, lithium, tranquilizers, phenothiazines, some antidepressants, and medicines that increase fluid retention. Side effects for prescription medications taken for other illnesses may reduce or increase weight and interfere with the absorption or excretion of nutrients.

Medications with the Potential for Causing Weight Gain

Adrenocorticosteroids used for the treatment of inflammatory and immunologic disorders affect carbohydrate, protein and fat metabolism. Even within therapeutic dosage, adverse effects include fluid imbalance, increased glycogen production, and stimulation of insulin release resulting in increasing fat deposits.

Anabolic steroids are used medically for androgen replacement in males, to reverse protein loss due to severe illness or trauma, and to treat aging and as a growth stimulant. Circulating testosterone in the body is reduced in obese individuals. The abuse of anabolic steroids in sports to “bulk up” to create large muscles may be due to fluid retention in the muscles.

Medications That May Cause Weight Gain by Edema (Fluid Retention)

• Clonidine is used to treat hypertension by inhibiting function of the sympathetic nervous system stimulates alpha adrenoreceptors in the arterioles.
• Phenothiazine drugs are used to treat serious mental and emotional disorders. As a group, they may cause loss of appetite, fever, or low body temperature in addition to retention of urine.
• Lithium is used for mood stabilizing for bipolar affective disorder. The mode of action is not definitive although it affects electrolytes, neurotransmitters, and converts inositol monophosphate to inositol. Lithium may cause weight gain through fluid retention or through another undefined mechanism.
• Estrogens is used for hormone replacement, as part of contraception, or to suppress ovulation may cause weight gain by increasing triglyceride levels and altering carbohydrate metabolism in addition to fluid retention.
• Indomethacin is a nonsteroidal antiinflammatory used in specific cases of acute gouty arthritis, ankylosing spondylitis, pericarditis, and pleurisy.
• Methyldopa is used to treat hypertension by inhibiting function of the sympathetic nervous system stimulates central alpha adrenoreceptors.

Medications to Decrease Nutrient Absorption

Medications prescribed for obesity are most commonly appetite suppressants and work by affecting the satiety centers of the brain and resulting in less food being consumed. Unique in action, orlistat is a prescription medication to treat obesity by blocking intestinal action of gastric and pancreatic lipases, the enzymes to break down and absorb fats. The result is a decrease in absorption of ingested fat by approximately 30 percent. In doing so, it may increase excretion of fat soluble vitamins A, D, E, and K.

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