It is well-known that body size and strength go hand in hand. The larger the body size, the greater the strength. Larger people can produce more force.

A better way to answer this question is to compare people of different sizes by comparing muscle mass. This leaves out the nonactive tissue otherwise known as adipose tissue or fat. Who's stronger muscle by muscle?

When using this approach overweight or obese adults have weaker handgrip, leg, and trunk strength. In some studies obese adults have higher knee extension strength. Scientists think this may be explained by the training effect of just carrying around more weight.

The differences in strength between obese and nonobese people probably have to do with metabolism of muscle cells. Further research is needed to understand this more clearly.