Being Thin and Being Lean: Is There a Difference?

Often people will look at a thin person and think to themselves; now that person is nice and lean. But is that really always the case? Does being thin have a direct relationship with being lean? In order to answer these questions we must examine what it means to be thin verses what it means to be lean.

Now you can define being thin as having a small circumference size. This would be denoted by small waist, arm, leg, and chest diameters as well as a low body weight all in relation to overall height.

The definition of being lean however is measured by overall body composition. This would be denoted by a low percentage of body-fat verses percentage of lean mass (muscle and bone). You may be surprised to know that thin people quite often are not lean at all. In fact, many thin people have a much higher body-fat percentage than you might think!

Now you may be thinking; how is that possible? Thin people don’t look fat so how can they have much body-fat? Consider this example:

Two women at 40 years old are both 5′ 7″ tall and both weigh 120 pounds. Women # 1 has a body-fat percentage of 25 and a waist size of 30. Woman # 2 on the other hand has a body-fat percentage of 16 and a waist size of 27. Both look thin, but woman # 2 is clearly leaner. What could be the cause of this? Why could both women be the same age, height, and weight but one is so much leaner than the other?

Atrophy is the term used for the natural loss of muscle that begins to occur in people at around the age of 25 who are sedentary or do no resistance training or strength training. By the time a person reaches their mid to late thirties a significant amount of muscle can be lost if no resistance training is being done.