Dr. Balentine received his undergraduate degree from McDaniel College in Westminster, Maryland. He attended medical school at the Philadelphia College of Osteopathic Medicine graduating in1983. He completed his internship at St. Joseph's Hospital in Philadelphia and his Emergency Medicine residency at Lincoln Medical and Mental Health Center in the Bronx, where he served as chief resident.
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
The balance between calorie intake and energy expenditure determines a person's weight. If a person eats more calories than he or she burns (metabolizes), the person gains weight (the body will store the excess energy as fat). If a person eats fewer calories than he or she metabolizes, he or she will lose weight. Therefore the most common causes of obesity are overeating and physical inactivity. Ultimately, body weight is the result of genetics, metabolism, environment, behavior, and culture.
Genetics. A person is more likely to develop obesity if one or both
parents are obese. Genetics also affect hormones involved in fat regulation. For
example, one genetic cause of obesity is leptin deficiency. Leptin is a hormone
produced in fat cells and also in the placenta. Leptin controls weight by
signaling the brain to eat less when body fat stores are too high. If, for some
reason, the body cannot produce enough leptin or leptin cannot signal the brain
to eat less, this control is lost, and obesity occurs. The role of leptin
replacement as a treatment for obesity is currently being explored.
Overeating. Overeating leads to weight gain, especially if the diet is
high in fat. Foods high in fat or sugar (for example, fast food, fried food, and
sweets) have high energy density (foods that have a lot of calories in a small
amount of food). Epidemiologic studies have shown that diets high in fat
contribute to weight gain.
A diet high in simple carbohydrates. The role of carbohydrates in weight
gain is not clear. Carbohydrates increase blood glucose levels, which in turn
stimulate insulin release by the pancreas, and insulin promotes the growth of
fat tissue and can cause weight gain. Some scientists believe that simple
carbohydrates (sugars, fructose, desserts, soft drinks, beer, wine, etc.)
contribute to weight gain because they are more rapidly absorbed into the bloodstream than complex carbohydrates (pasta, brown rice, grains, vegetables, raw
fruits, etc.) and thus cause a more pronounced insulin release after meals than
complex carbohydrates. This higher insulin release, some scientists believe,
contributes to weight gain.
Frequency of eating. The relationship between frequency of eating (how
often you eat) and weight is somewhat controversial. There are many reports of
overweight people eating less often than people with normal weight. Scientists
have observed that people who eat small meals four or five times daily, have
lower cholesterol levels and lower and/or more stable blood sugar levels than
people who eat less frequently (two or three large meals daily). One possible
explanation is that small frequent meals produce stable insulin levels, whereas
large meals cause large spikes of insulin after meals.
Slow metabolism. Women have less muscle than men. Muscle burns
calories than other tissue (which includes fat). As a result, women have a
slower metabolism than men, and hence, have a tendency to put on more weight
than men, and weight loss is more difficult for women. As we age, we tend to
lose muscle and our metabolism slows; therefore, we tend to gain weight as we
get older particularly if we do not reduce our daily caloric intake.
Physical inactivity. Sedentary people burn fewer calories than people who
are active. The National Health and Nutrition Examination Survey (NHANES) showed that
physical inactivity was strongly correlated with weight gain in both sexes.
Medications. Medications associated with weight gain include certain
antidepressants (medications used in treating depression),
anticonvulsants (medications used in controlling
seizures such as carbamazepine
[Tegretol, Tegretol XR , Equetro, Carbatrol] and
valproate [Depacon, Depakene]),
diabetes medications (medications used in lowering blood sugar such as insulin, sulfonylureas, and thiazolidinediones), certain hormones such as oral
contraceptives and most corticosteroids such as
prednisone. Weight gain may also
be seen with some high blood pressure medications and antihistamines. The reason for the weight gain with the medications differs for each medication. If this is a concern for you, you should discuss your medications with your physician rather than discontinuing the medication, as this could have serious effects.
Psychological factors. For some people, emotions influence eating habits.
Many people eat excessively in response to emotions such as boredom, sadness,
stress, or anger. While most overweight people have no more psychological
disturbances than normal weight people, about 30% of the people who seek
treatment for serious weight problems have difficulties with binge eating.