Diet texture, moisture and starch type in dietary obesity.

A series of experiments demonstrated that the texture of a diet has less effect on growth than does the water content. Rats fed diets containing 50-71% water become obese. On the other hand, diets containing as little as 30% or as much as 75% water failed to increase growth. Varying the concentration of the suspending agent (xanthan gum) from 0.5% to 2% greatly altered the viscosity of liquid diets but had no reliable effect on growth. Diets containing gelatinized starch became semi-solid when water was added but the rats still grew faster when fed the moist rather than the dry gelatinized starch diets. However, feeding a diet containing a very high level of gelatinized starch reduced growth independently of the moisture content. Rats fed a dry powdered diet gained weight at about the same rate as rats fed a pelleted diet. These results indicate that the moisture content of a diet has a major influence on its ability to induce obesity. The type of starch fed to the rats also seems to be an important determinant of growth rate.