High-carb meals better in curbing appetite amongst the obese: Study

The study looked into the impact of macronutrients on the effects on satiety and desire for certain foods. Additional results also revealed that a high-carbohydrate meal was more effective in reducing a desire for high fat foods.

Recent evidence suggests the desire of foods encountered after consumption is closely linked to the perceived taste and energy content. This can also influence appetite and energy intake​​.

For example, a heightened liking for high-fat, high-sweet foods have been noted in overweight and obese individuals​​ and binge eaters​​.

Despite this, the effect of macronutrient composition on food desire has received little attention, and existing data has proved contradictory.

Research details ​

Researchers from Sheffield Hallam University and the University of Leeds, enrolled 65 overweight and obese individuals in a series of tests designed to assess satiety and the sensations associated with consuming food (hedonics).

The participants completed two separate test meal days in a randomised order in which they consumed high-fat/low-carbohydrate (HFLC) or low-fat/high-carbohydrate (LFHC) foods.

Satiety was measured using appetite ratings and satiation was assessed by intake at meals.

Hedonic measures of liking (subjective ratings) and wanting (speed of forced choice) for a range of HFLC and LFHC foods were also taken before and after HFLC and LFHC meals with identical energy content (isoenergetic).

The team found participants felt fuller after consuming LFHC meals compared with the HFLC foods, despite a lower energy intake.

More significantly, consumption of the LFHC meal reduced the desire for HFLC foods. Participants felt more desire for the isoenergetic HFLC meal after consuming a LFHC meal. This meal failed to suppress the hedonic appeal of subsequent HFLC foods.

Previous studies ​

Although the effects of dietary fat and carbohydrates on satiety are well documented, little is known about the behavioural mechanisms that promote overconsumption following the consumption of energy-dense, high-fat foods.

Previous studies have identified carbohydrate intake as having a more significant role in causing overconsumption and weight gain than dietary fat.

Although this view has been hotly contested​​, it has long been known that dietary macronutrients exert a hierarchical effect on appetite-related processes such as satiety and short-term food intake​​.

When expressed relative to energy content rather than weight of food, protein exerts the strongest effect on satiety, followed by carbohydrate, whilst fat exerts the weakest effect​​.

The researchers pointed towards changes in the physiological signals arising from the fat and carbohydrate content of the meals as the cause of differences in satiety seen in the study.

It is thought that the macronutrient composition of meals control the secretion of satiety hormones such as glucagon-like peptide-1​​ and peptide YY​.​

Despite the use of mixed macronutrient meals in the study, the carbohydrate content of the HFLC meals would have still stimulated the release/suppression of satiety hormones, but to a lesser extent than the LFHC meal.

This may help account for why the differences in degree of satiety between conditions were smaller under isoenergetic feeding conditions, a finding that has been previously reported​.​

In commenting on the effects of macronutrient composition on food hedonics, researchers thought it interesting that, when hungry, individuals preferred HFLC foods relative to LFHC foods to a similar degree during both conditions.

This preference changed away from HFLC foods in the fed state during the LFHC condition, but remained during the HFLC condition.

“This might counter-intuitively suggest that individuals increased their preference for the more satiating LFHC foods in the fed state during the LFHC condition despite already being more satiated,”​ the study noted.

“The decreased appeal bias scores in the fed state during the LFHC condition are more likely to reflect a reduced preference for HFLC, rather than an increased preference for LFHC foods per se.“​

Previous studies have shown that, when satiated, individuals tend to experience a reduced preference for HFLC​​ compared with LFHC under ad libitum feeding conditions​​.

Therefore, observations in the present study that demonstrated a sustained liking and wanting for high-energy foods when satiated may throw new light on how high-fat diets lead to overconsumption.

Source: British Journal of Nutrition​

Published online ahead of print, doi.org/10.1017/S0007114516000775​​

“Differing effects of high-fat or high-carbohydrate meals on food hedonics in overweight and obese individuals.”​

Authors: Mark Hopkins, Catherine Gibbons, Phillipa Caudwell, John Blundell and Graham Finlayson.

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