Are high-fat and low-fat consumers distinct phenotypes? Differences in the subjective and behavioural response to energy and nutrient challenges.

OBJECTIVE

To characterise the appetite control in habitual high fat (HF) and low fat (LF) phenotypes.

DESIGN

Four treatment conditions for each subject group in a fully repeated 2 x 2 x 2 measures design.

SETTING

The Human Appetite Research Unit at Leeds University, Psychology Department.

SUBJECTS

Eight lean HF (mean % fat intake-46.7% daily energy) and eight lean LF (mean % fat intake - 29.9% daily energy) were recruited from the staff/student population of Leeds University.

INTERVENTIONS

All subjects were provided with either a low (2129 kJ) or high (3801 kJ) energy meal at midday and the capacity for compensation was later measured by nutrient challenge (ad libitum consumption of either high fat or high CHO foods). Satiation and satiety were assessed by changes in energy and nutrient intakes, hunger, fullness and food preferences.

RESULTS

The energy and nutrient manipulations gave rise to different levels in the rated intensity of hunger between HF and LF (P < 0.01). HF rated their baseline hunger at a higher level than LF, and the nutrient induced changes in hunger had a much greater amplitude. HF consumed significantly more energy from the high fat meals than from the high CHO meals (P < 0.05); this effect was not observed in LF. HF ate more energy and a greater weight of the high fat foods but less energy and smaller weight of the high CHO foods than did the LF. HF rated the high fat and high CHO foods equally satisfying, tasty and filling, whereas LF indicated a preference for high CHO foods (P < 0.05).

CONCLUSIONS

The appetite control in habitual high and low fat consumers is different. HF 'passively overconsume' fat whereas this effect is weak in LF. The HF ate a constant weight of food whereas LF ate a more constant level of energy. HF could not distinguish between high and low fat foods suggesting that they were intrinsically insensitive or 'taste adapted' whereas LF were fat sensitive. The clear differences disclosed in response to signals generated by the characteristics of ingested food (weight, energy, nutrient composition, taste) suggest that habitual high and low fat consumers can be regarded as distinct behavioural phenotypes. The different styles of appetite control could arise from: (a) intrinsic physiological differences, or (b) a system which is adapted to deal with a particular type of diet.