Causes of Obesity


The main cause of obesity is when energy in is more than energy out.  When energy intake is more than energy output the body stores the extra energy as fat. Energy intake is the amount of energy in food and drink. Energy expendature is variable and is depends on age, sex, the amount of muscle mass, genetic factors, existing disease states, ambient temperature, and activity level.

One pound is equal to 3500 calories. To gain one pound of fat, an excess of 3500 calories is needed. If an individaual with a stable weight eats one small chocolate bar (about 100 calories), than in 35 days that individual would gain one pound (assuming every thing else stays stable).




Many societal factors cause obesity

• Long-work schedules
• Large portion sizes at many restaurants
• Lack of access to healthy food and easy access to junk food 
• Many work places have vending machines with chips, candy bars and sodas.
• Sporting events have snack bars with foods like nachos, popcorn, beer and soda
• The abundance of high calorie food is common

Americans are sedentary. People are more involved with spectator sports than participating in sports. Extra calories consumed that are not expended are stored as fat.

Chronic sleep deprivation may promote weight gain.

Genetics are also related to obesity. Genes have a strong influence on being overweight or obese and also affects the location and amount of fat.

Families also share food and activity habits. Parents who have an abundance of fruits and vegetables in the house and minimal high calorie junk food in the house tend to have children who eat better than a household with an abundance of chips, doughnuts and ice cream.

Certain health conditions increase the incidence of obesity. Hypothyroidism, Cushing’s disease, depression and polycystic ovarian syndrome increase the chance of obesity. Medications such as antidepressants, antipsychotics, anti-seizure medications, lithium, insulin, diabetes medicine, and steroids may lead to weight gain.