The Causes of Obesity

The causes of obesity are both genetic and environmental. Dr. Joseph Goldstein, the nobel winner in medicine, said 18 years ago, “Most obesity patients have a genetic pre-disposition, likely linked to one of the hormones controlling hunger.”

Today, many labs are conducting several studies to help explain the cause of obesity and eventually provide a cure.

The interplay of genetic and environmental factors cause obesity, although there is a tremendous amount still unknown.

A large proportion of work is on the genetics of obesity. Scientists are mapping out the genetic landscape, determining which genes and hormones play a role in pre-disposing a person to obesity.

However, as it stands today, the causes of obesity remain largely unknown.

Let’s think of the causes of obesity in terms of a cycle. This cycle is fed by abnormal hunger signals (genetics), age, malnourishment, lack of exercise and, believe it or not, dieting.

The cycle might look something like this:

Natural weight gain refers to aging and your unique genetic profile. Unnatural weight gain includes the things you do to feed the obesity cycle.

Let’s now look into the natural causes of obesity.

Natural or “Age Related” Weight Gain

It’s natural to gain weight as you age. It’s unnatural to develop obesity. The cause of obesity go beyond the natural causes weight gain, which include aging, a lower metabolic rate (MR), and muscle loss.

The MR is the amount of energy your body needs to perform normal functions. As you age, the energy required to run normal functions decreases.

When people tell you to increase your metabolism, the MR is what they mean. Unfortunately, you can not increase your MR! It drops as you age and that’s that.

You can increase your metabolic rate for a short period of time, but in the long run, it will drop. Why does this matter?

Good Question.

Why does it matter if your metabolic rate drops?

    • Let’s suppose that you ate enough food to equal 10 units of energy. Your body decides that three units are needed for exercise, 2 units are needed for digesting food, and 5 units are needed for everyday functions, the BMR.
      Total Energy Expended = BMR(5) + Digestion(2) + Exercise(3) = 10
      At the end of the day, you have no energy left. The energy balance is zero. You ate 10 units and used 10 units.
      Total Energy = 10(in) – 10(out) = 0 units


    • The next day, you eat another 10 units of energy. But your body requires only 3 units of energy for the resting metabolic rate. Nothing else changes…exercise needs 3 units and digestion needs 2 units.
      Total Energy Expended = BMR(3) + Digestion(2) + Exercise(3) = 8
      Units Left = Total energy you ate(10) – Total Energy Expended(8) = 2


    • Now what? Will you waste the 2 extra units of energy? Never! The human body will not waste energy. Instead, the extra energy is stored as fat.
    • You just stored 2 units of fat for a rainy day. The more fat stored, the more you weigh. Imagine this process repeating itself day in and day out, meal after meal…It does.

Bottom line: As you age, the required energy to function decreases. Unless you decrease the amount of food you eat or start exercising, you will gain weight!

This is age related weight gain, the natural process.

Now that we have discussed some of the causes of obesity, lets talk about what you can do about it.