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Energy Metabolism and Appetite Control
Published in Ruth B.S. Harris, Appetite and Food Intake, 2017
Mark Hopkins, John E. Blundell
It has also been suggested that day-to-day food intake is regulated via nutrient-specific appetite control mechanisms rather than an energy-based regulatory system reliant on the energy content of the diet. In particular, the protein-leverage hypothesis (Simpson and Raubenheimer 2005) proposes that dietary protein intake is (i) tightly regulated, (ii) independent of the regulation of dietary fat and carbohydrate intake, and (iii) prioritized over the energy content of the diet. It has been proposed that such regulatory control can lead to excess EI when a diet is low in protein as fat and carbohydrate are consumed in excess to “compensate” for the perceived protein deficit by “leveraging” dietary fat and carbohydrate intake (Sørensen et al. 2008). Evidence for “nutrient-specific appetites” exists in a range of animal models (see Morrison and Laeger 2015 for a review) Furthermore, experimental and cross-sectional survey data suggest that humans also compensate for reductions in dietary protein via increased food intake and, in so doing, consume excessive amounts of dietary fats and carbohydrates (Gosby et al. 2014). While such data fit with the notion of a protein-stat or amino-stat, such leverage by appetites for specific nutrients suggests that EI is not linked to “energy sensing” mechanisms (that reflect energy need). However, the underlying mechanisms behind such nutrient-specific appetite control mechanisms in humans remain poorly defined (Morrison and Laeger 2015). Furthermore, it is quite feasible that a nutrient-specific protein-sensing mechanism could function alongside a regulatory mechanism that reflects energy need.
ENTRIES A–Z
Published in Philip Winn, Dictionary of Biological Psychology, 2003
Humans and animals are unable to synthesize many crucial nutrient substances, and therefore must consume them in food. If a diet lacks a particular nutrient or particular set of nutrients over a long period of time, then malnutrition may result. But when a wide array of nutrients is available, most individuals seem to eat a mostly balanced diet most of the time. The question of how an appropriate balance of nutrient intake is maintained, and whether there is a SPECIFIC APPETITE (or SPECIFIC HUNGER as it is also known) for each type of nutrient that is needed, has been the focus of much research. There are a very few nutrients for which a clear specific appetite seems to be triggered whenever a physiological deficit occurs for that nutrient. The most robust specific appetite is SALT APPETITE or SODIUM APPETITE, which is directed specifically towards salty tasting foods during states of physiological sodium depletion. Aside from salt, however, most classes of nutrients do not have distinct tastes (see GUSTATION). That poses the question of how the brain might recognize whether a food contained a particular needed mineral, vitamin or other nutrient. This problem appears to have had a major consequence: aside from salt appetite, there are very few specific appetites for nutrients that are triggered innately in states of physiological depletion. Only two other nutrients, both of which are minerals, have been indicated to have specific appetites that can stand up to rigorous experimental scrutiny: IRON and CALCIUM. All other states of specific nutrient depletion appear to act via a generalized LEARNED APPETITE mechanism rather than through innate specific appetites. Most of them produce symptoms of illness and malaise over the long term. When a particular diet is accompanied by such symptoms, two things appear to happen. First, a learned aversion (see FOOD-AVERSION LEARNING) begins to develop for the foods that are associated with the illness. This developing aversion leads individuals to try new foods, and to avoid the old one, whenever the opportunity arises. Second, if a particular new food is accompanied by dramatic recovery from the illness, which may happen if it contains the missing nutrient, a moderate preference for that particular new food may be learned. This combination of biopsychological mechanisms leads most animals and humans to consume an adequately balanced diet of nutrients over the long term.
Infant sex differences in human milk intake and composition from 1- to 3-month post-delivery in a healthy United States cohort
Published in Annals of Human Biology, 2021
Erin K. Eckart, Jennifer D. Peck, Elyse O. Kharbanda, Emily M. Nagel, David A. Fields, Ellen W. Demerath
In summary, the evidence in humans for differential maternal investment in male vs. female infants in terms of amount of milk provided indicates differences are small, and inconsistent across studies. This conclusion is based on few studies to have examined the question to date, and in a wide range of populations which may or may not reflect the types of environmental forces that would reveal the hypothesised phenomenon. Also, human studies suffer from the difficulty in accurately disarticulating differences in maternal supply for male and female infants from infant milk intake differences, which are not only determined by supply but also by infant-specific appetite, sleep, growth, and feeding behaviours.