Obesity is a rising concern in the United States, as up to seventy percent of the population is considered overweight and approximately 35 percent are obese. Obesity is related to increased morbidity from cardiovascular disease, diabetes mellitus, cerebrovascular accidents, hypertension, and liver disease. The body mass index is calculated based on a patient’s weight and height. A person is considered overweight with a BMI greater than 25 and is in the obese category with a body mass index greater than 30. Increased weight circumference or the accumulation of adipose tissue in the upper body and abdominal cavity is associated with increased risk of insulin resistance, cardiovascular disease, and stroke. A waist circumference greater than 35 inches in women or 40 inches in men is considered to place an individual at increased health risk.
Weight reduction goals average from 0.5 to 1 pound a week for approximately 10 percent over 6 months. Weight loss management should include a combination of reducing caloric intake, increasing physical activity, behavior modification, and drug therapy. Bariatric surgery is only indicated for patients with a body mass index greater than 40, in which conservative treatment modalities have been unsuccessful. The two most widely used surgical procedures include the gastric band and the Roux-en-Y gastric bypass surgery.
Liraglutide (Victoza) is approved for chronic weight management because of its ability to decrease appetite and produce reduction in caloric intake. The class of medications that affect incretin hormones by directly mimicking the same action of the natural hormone by directly activating the receptor sites are the glucagon-like peptide (GLP-1) receptor agonists. Liraglutide can be given once daily. Clinical trials have demonstrated that liraglutide reduces rates of cardiovascular deaths and adverse cardiovascular events in patients with type 2 diabetes mellitus and high cardiovascular risk. Side effects include gastrointestinal upset such as vomiting, diarrhea, anorexia, or dyspepsia.
Lorcaserin (Belviq) is a selective type 2 serotonin (5-HT2c) agonist which causes a feeling of satiety and reduces appetite by stimulating the hypothalamic and mesolimbic pathways. Lorcaserin has been associated with reduced waist circumference, decreased insulin resistance, and a reduction in LDL cholesterol. Patients with diabetes mellitus can have increased episodes of hypoglycemia when combined with Lorcaserin. Contraindications include valvular heart disease, pulmonary hypertension, or blood dyscrasias.
Orlistat, a lipase inhibitor, is not as effective as phentermine, with a total weight loss around 2 percent. Orlistat has a mechanism of action on the gastrointestinal tract to decrease fat absorption. The drug prevents the breakdown of triglycerides by causing inhibition of pancreatic and gastric lipases. Patients prescribed Orlistat must reduce their caloric intake to less than 30 percent of calories coming from fat.
A combination medication approved for weight loss is bupropion with naltrexone (Contrave). The combination of an opioid antagonist with the effects of a norepinephrine-reuptake inhibitor regulates appetite in the hypothalamus and mesolimbic system. This medication should not be used in patients with mental health illness or major depressive disorder. Other adverse effects include insomnia, nausea, headache, and constipation.
Lastly, phentermine can be used as monotherapy for weight loss in certain patient who meet the requirements to achieve weight reduction goals.
Next, a combination of phentermine and topiramate (Qsymia) are associated with the greatest amount of weight loss. Phentermine is stimulant and should bot be given in people with high blood pressure or cardiovascular disease.