HIGH-FAT FOODS OVERCOME THE ENERGY-EXPENDITURE INDUCED BY HIGH-INTENSITY CYCLING OR RUNNING

Objective: To examine the effects of two types of vigorous exercise [c ycling (CYC) and running (RUN)] and diet composition on appetite contr ol. Design: Two studies using separate groups of subjects were used fo r the two forms of exercise. The studies used a 2 X 2 design with the factors being exercise and diet composition. Therefore both studies ha d four treatment conditions and used a repeated measures design. Setti ng: Both studies took place in the Human Appetite Research Unit at Lee ds University. Subjects: Twenty-four lean, healthy males were recruite d from the student staff population of Leeds University. Interventions : For both studies a control (no-exercise) and a vigorous exercise ses sion (70% VO2 max) was followed by a free-selection lunch comprising h igh-fat/low-carbohydrate foods or low-fat/high-carbohydrate foods, dur ing which energy and macronutrient intake was monitored. Motivation to eat was measured by visual analogue scales and by the latency to voli tional onset of eating. Energy intake for the remainder of the day (ou tside of laboratory) was monitored by providing the subjects with airl ine-style food boxes. Results: Both CYC and RUN produced similar effec ts on appetite responses. Both CYC and RUN induced a transitory suppre ssion of hunger (P < 0.01 and P < 0.05) and a delay to the onset of ea ting (P < 0.001). Exercise (whether CYC or RUN) had no significant eff ect on the total amount of food eaten, but there was a significant eff ect of lunch type. When provided with the high-fat/low-carbohydrate fo ods energy intake was significantly elevated (CYC: P < 0.001; and RUN: P < 0.0001). Both types of exercise induced a short-term negative ene rgy balance when followed by the low-fat/high-carbohydrate foods (P < 0.001), which was completely reversed (positive energy balance) when s ubjects ate from the high-fat/low carbohydrate foods. Conclusions: The se results indicate that eating high-fat foods can prevent exercise in ducing any (short-term) negative energy balance. Therefore, in order f or exercise to have a significant impact on weight control, it is impo rtant to consider the energy density of the accompanying diet. Despite the different physiological aspects of cycling and running, they did not display different effects on appetite. Sponsorship: This work form s part of a project supported by the Sports Council of the UK. Descrip tors: cycling, diet composition, exercise, fat, running