An increased consumption of fruits and vegetables (F&V) has been suggested as a way to limit, or even lower, energy and fat intakes. The present study examined the effects of incorporating F&V supplements into the diets of adults who reported consuming <240g (three portions) of F&V per d on energy and fat intakes, and change in body weight, over 8 weeks using a randomised parallel design. Thirty-four males and twenty-eight females (age 42·6 (sd 11·1) years, BMI 23·7 (sd 2·7) kg/m2) were each provided with supplements of 0, 300 or 600g F&V per d. Food, nutrient and energy intakes were measured before, during and at the end of the supplementation period using 7 d weighed records. Mean daily energy intakes were not different among the three groups before (P=0·151) or during the supplementation periods (P=0·407), although changes in energy intakes over the study period tended to be more positive with increasing amounts of F&V supplements (P=0·078). There was no difference in changes of body weights during the study (P=0·242). Carbohydrate (P<0·001), sugar (P<0·001), fibre (P<0·001) and weight of food consumed (P=0·022) increased in the treatment groups. There were no significant differences, or changes, in fat intakes among the three groups. Consumption of mandatory F&V supplements for 8 weeks produced beneficial changes in diet composition, but did not result in lower reported energy or fat intakes, and did not result in loss of body weight.