Losing a tenth of your weight is enough to change the outcome

Obesity is a disease: having too much body fat. It is not the same as
being overweight, which means weighing too much. Both mean a weight greater
than is considered healthy for your height, and the distinction matters
because the treatments and the risks attach to body fat rather than to the
number on the scale.

Body Mass Index compares weight to height. An adult with a BMI of **30 or
more** has obesity; 40 or higher is severe obesity. Risk rises further when
the extra fat is carried around the waist.

How BMI misleads, and what is used alongside it

BMI does not distinguish between fat, muscle and bone. It overestimates
body fat in athletes and muscular builds, and underestimates it in older
people and others who have lost muscle. That is why a diagnosis is not a BMI
calculation on its own. A provider will also:

• Ask about your health history — weight history, past weight-loss efforts,
  how physically active you are
• Do a physical exam — height, weight, vital signs, listening to heart and
  lungs
• Order blood or imaging tests for known problems and other weight-related
  conditions
• Check your waist size, because fat around the abdomen rather than the
  hips raises risk specifically

Why it happens

Obesity develops over time from taking in more calories, through food and
drink, than are used by physical activity and daily living; the surplus is
stored as fat. **The right balance between calories and activity is different
for everyone**, which is why a plan that worked for someone else may not work
for you.

Many things affect body weight: certain medicines and medical conditions, and
your genetic makeup, eating habits, sex, race or ethnicity and physical
activity level.

What it raises the risk of

Type 2 diabetes. Heart disease. High blood pressure. Stroke. Metabolic
syndrome. Osteoarthritis. Sleep apnoea. Pregnancy problems. Fertility
problems. Some cancers.

A larger body makes the heart work harder and puts extra pressure on the
joints, which accounts for several of those directly.

The number worth remembering

**Losing 5 to 10% of your weight can delay or prevent some of those
diseases.** At 200 pounds that is 10 to 20 pounds — considerably less than
most weight-loss goals, and enough to change the medical picture.

Treatment depends on your overall weight, other health conditions and your
willingness to take part in a plan. A provider can tell you what a healthy
weight is for you, help set goals, and refer you to specialists in nutrition
or weight loss. Options include:

• Dietary changes and exercise goals, aimed at losing weight safely and
  keeping it off long term
• Counselling or support groups, for encouragement and for understanding
  what is behind the weight changes
• Weight-loss medicines
• Weight loss procedures or surgery, for severe obesity or serious
  obesity-related health problems where enough weight has not come off

*Source: National Institute of Diabetes and Digestive and Kidney Diseases,
via MedlinePlus.*