The authors evaluated the role of a high-protein, low-calorie, polyunsaturated 
fatty-acid (PUFA) -supplemented diet on anthropometric parameters, 
erythrocyte-membrane fatty-acid composition, and plasma antioxidant defenses of 
nonprofessional volleyball athletes. The athletes were divided in two groups: 
One (n = 5) followed the Mediterranean diet, and the other (n = 6) followed a 
high-protein, low-calorie diet with a 3-g/day fish-oil supplementation. All the 
athletes had anthropometric measurements taken, both at the beginning and at the 
end of the study, which lasted for 2 months. Body-mass index and total body fat 
were significantly diminished in the second group, while they remained unchanged 
in the first. Plasma total antioxidant activity (TAA) was significantly 
increased in the plasma of both groups, with no differences between the groups, 
suggesting that physical activity, not the different diets, is the main 
contributor to the increase of plasma TAA. The second group showed a significant 
increase in erythrocyte-membrane PUFA content and in the unsaturation index 
value (UI) because of the fish-oil supplementation.A high-protein, 
low-carbohydrate, fish-oil-supplemented diet seems to be useful only when the 
aim of the diet is to obtain weight loss in a short-term period. The significant 
increase in the UI of erythrocyte membranes indicates the potential for harm, 
because a high intake of PUFA might increase susceptibility to lipid 
peroxidation not counterbalanced by a higher increase in TAA. Adherence to the 
Mediterranean diet seems to be the better choice.