Sensory Stimulation and Palatability

Palatability can be measured as the subjective preference for a food, its subjective pleasantness, or indeed the amount (in grams) of a food a subject eats. The relative palatability of a food can be determined by choice tests or taste tests relative to other standard ingestants (e.g., the 5% sugar solution). However, there has been much more controversy over the actual definition of palatability. In general the palatability of a food can be thought of as: (1) the momentary subjective orosensory pleasantness of a food; or (2) its sensory capacity to stimulate ingestion of that

Environmental influences on human

Appetite research

Free living

Laboratory

Less precision and accuracy

Less control, greater ecological relevance

Greater precision and accuracy Greater control, less naturalistic

'Natural setting' studies

Intervention studies

Laboratory studies

'Natural setting' studies

Intervention studies

Laboratory studies

Natural environment

Natural environment

Artificial environment

Behavior less disrupted

Behavior disrupted

Behavioral artifacts

No controlled manipulations

Controlled manipulation

Well-controlled manipulation

Variable environment

Variable environment

Constant environment

Figure 3 The constraints and limitations that the experimental environment places on studies of human feeding. In general the environment ranges from totally free living, which is realistic but very difficult to make measurements in, to the laboratory where measurements are easy but may be contaminated by artifacts due to the artificiality of the laboratory surroundings.

Figure 3 The constraints and limitations that the experimental environment places on studies of human feeding. In general the environment ranges from totally free living, which is realistic but very difficult to make measurements in, to the laboratory where measurements are easy but may be contaminated by artifacts due to the artificiality of the laboratory surroundings.

food. However, the second definition should not be taken to indicate that there is a direct correlation between the perceived palatability of a food and the amount of that food which is ingested. As with hunger, the coupling between the expressed sensation and the amount of food or energy ingested is loose. This definition takes account of the fact that the palatability of the food is jointly determined by the nature of the food (smell, taste, texture, and state), the sensory capabilities and metabolic state of the subject, and the environment in which the food and subject interact. Palatability is therefore not stable; indeed, the palatability of a food typically declines as its own ingestion proceeds. Work on military personnel suggests that the decline in preference for highly preferred foods (e.g., chocolate) is greater than that for staple foods such as bread, which exhibit more stable preference profiles. Palatability can be dissociated from sensory intensity since sensory intensity increases with the concentration of the compound or food being tasted; palatability generally shows a parabolic n-shaped curve with increasing sensory intensity of the food. Palatability can be conditioned, as can aversions. Palatability of a food generally increases with food deprivation.

Because of the mutable nature of palatability and sensory preference the role that they play in determining EI and degree of overweight are unclear. Short-term experiments suggest that more preferred foods stimulate hunger and food intake. Recent work in American and French consumers suggest that on a palatability scale of 1-7 subjects rarely select any food below a score of 3 and that palatability does increase the size of meals. But these works do not address energy balance. Indeed, virtually no published evidence supports the notion that altering dietary palatabil-ity or sensory variety per se will influence longer term energy balance of human subjects, despite the common perception that increasing dietary palatability will increase intake. This perception is so strong that the food industry feels unable to sacrifice the palatability of their products in developing healthier options, as the risk of decreased consumer acceptance is believed to be too high.

Certain combinations of the sensory and nutritional profiles of foods (e.g., sweet, high-fat foods) are conducive to overconsumption. This effect is often due to the combination of sensory stimuli and the postingestive effects of the food, which re-enforce each other. The individual sensory and nutritional stimuli in isolation are often less effective. Thus, cafeteria regimes, which can produce obesity in rats, typically alter the composition of the diet by increasing its fat content. When rats are given petroleum jelly in chow as a fat mimetic, they initially prefer this diet to normal chow. This preference soon becomes extinct, suggesting that sensory factors alone do not maintain preference.

Dieting Dilemma and Skinny Solutions

Dieting Dilemma and Skinny Solutions

The captivating thing about diets is that you don't get what is researched or predicted or calculated but rather, you get precisely what you expect. If the diet resonates with you then it will likely work, if it doesn't resonate, it won't.

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