Overweight or Obese: What’s the Difference?

Why is life so complicated when simple things should remain simple and complex things complex? I’m talking about health specialists who confuse by using the words obesity and overweight interchangeably.

People want to know if a child is overweight, obese or what? Historically, overweight and obesity have been used interchangeably. I have never liked to use these words as synonyms. Properly speaking an obese person or child is someone who carries around an excessive amount of body fat. An overweight child, is one who weighs more than what is recommended on the growth height/weight charts at the doctor’s office. It is possible, however, for a child to be overweight and obese; overweight but not obese; obese but not overweight or underweight and obese!

While most scientists agree with what I have just said, many people prefer to call a child who exceeds the 85th percentile in body weight, overweight, or less intrusively “at risk for overweight”. That means the child weighs more than 85% of other children of their gender, age and weight. Obesity, on the other hand, refers to those children who are in the 95th percentile (upper 5% or more).

These percentile rankings appear to be a simple method for “estimating” kids who are overweight or obese. Unfortunately that is not the case. With the percentile method, the amount of body fat on the child is ignored. Sadly, a child’s amount of body fat is the most crucial part of the overweight-obesity discussion.

The problem with using overweight as the key definition is that it is limited to comparing a child’s weight to their peers. That is, how do they stack up on height/weight charts or body mass index (BMI) scores? While these height/weight contrasts provide epidemiologists (people who study the incidence, distribution and control of diseases) with some information on what is going on among children and weight and growth, it does not tell the entire story. Nor does it accurately address the future health problems (metabolic syndrome diseases) of the “overweight” child, now or later in life.

Since obesity refers to excess body fat, it is better for scientists to utilize actual measurements of body fat of children, regardless of their weight. That’s because a child’s weight may be at the 50th percentile (average) yet he/she carries too much body fat (obese). On the other hand a child may be at the 95 percentile weight and height wise and be very lean. The only valid ways that one can understand whether a child is too fat or not is to use tests such as skin folds, trunk fat, various anthropometric measurements, underwater weighing, bioelectrical analysis, DEXA scanning and air displacement plethysmography. These are tests I will begin to address next time.

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