Weight Gain from Simple Overeating. II. Serum Lipids and Blood Volume 1

Abstract

Twenty physically healthy schizophrenic men increased their caloric intakes without changing their physical activity. The diet was substantially constant and fully adequate in proteins and vitamins at all times, the extra calories being provided by adding carbohydrates and a small amount (about 1/3 of the extra calories) of mixed fats to the standard diet. Thus the total fat intake increased though the proportion of calories from fats fell slightly. Average calorie increases for 20 weeks ranged from 8% to 39% and these produced weight gains from 2.5 to 22.2 kg, the average gain being about 0.5 kg/week. The average total serum cholesterol concentration rose 20 mg/100 ml during the first 5 weeks of overeating and then remained substantially constant at the same level during the next 15 weeks though weight gain continued at the same rate as during the first five weeks. The rise in serum cholesterol concentration in the various individuals tended to be proportional to the rate of weight gain. The concentration of the Sf 12-20 lipoprotein fraction in the serum, measured in the ultracentrifuge, tended to increase from the 10th to the 20th week of overeating though the total serum cholesterol remained constant. Weight gain tended to be associated with increase in circulating plasma and blood volume during the first weeks of overeating with no further change thereafter. A hypothesis as to the role of cholesterol in fat transport is presented which seems to explain the increase in serum cholesterol on a high fat diet and in over-nutrition with a positive calorie balance; the stability of the serum cholesterol during calorie equilibrium or in a steady state of continuing over-nutrition; the failure of serum cholesterol to rise when diet calories and energy expenditure are both increased in parallel; and the decrease in serum cholesterol on a low fat diet and in negative calorie balance.