Exploring effects of flavour-nutrient inconsistency and dietary variability (BBSRC)
The current food environment is characterised by an endless variety of cheap, readily-available and highly-palatable foods. While it is generally recognized that this ‘obesogenic’ food environment is responsible for the increases in overweight and obesity, the specific mechanisms by which the current food environment promotes overeating are still being explored.
How do you manage your calorie intake when you aren’t exactly sure how many calories you’ve eaten? The effect of flavour-nutrient inconsistency on the learned controls of energy intake.
One way in which the current food environment could promote weight gain is by increasing uncertainty about what we’ve eaten. In order to maintain a stable body weight, one must be able to moderate one’s food intake—eating less at some times and more at others. This is partly accomplished by learning to use the orosensory properties of a food (i.e., taste, smell) to predict how caloric and/or satiating it will be. This kind of ‘flavour-nutrient’ learning helps us to make judgments about what and how much to eat. However, the increased availability of several different varieties of the same food product could make it difficult for us to reliably predict the energy content of a food or the satiation it will deliver. This could reduce our ability to moderate our food intake throughout the day, leading to overeating and weight gain.
A similar phenomenon has recently been demonstrated in studies exploring ‘sweet-calorie’ learning in rats. Whereas animals will usually learn to rely on sweetness to signal increased energy, this ability can be disrupted by providing the animal with artificial sweeteners (which provide sweet taste without any reliable increase in calories). Impairing this ‘sweet-calorie’ learning weakens the ability of rats to control their intake of sweet foods, leading to overeating and weight gain. Researchers in the NBU are currently exploring whether similar experiences could promote uncertainty about the caloric and satiating quality of food in humans, and whether this is a risk factor for obesity.
Recent peer-reviewed papers:
- Keenan, GS, Brunstrom, JM & Ferriday, D 2015, ‘Effects of meal variety on expected satiation: Evidence for a ‘perceived volume’ heuristic’. Appetite, vol 89., pp. 10-15. Click here to view
- Hardman, CA, Ferriday, D, Kyle, L, Rogers, PJ & Brunstrom, JM 2015 'So Many Brands and Varieties to Choose from: Does This Compromise the Control of Food Intake in Humans? PLOS ONE, vol 10 (4)., pp. e0125869. Click here to view
- Martin, AA, Hamill, LR, Davies, S, Rogers, PJ & Brunstrom, JM 2015 Energy-dense snacks can have the same expected satiation as sugar-containing beverages. Appetite, vol 95 (1), pp. 81-88. Click here to view
- Schiöth, HB, Ferriday D, Davies SR, Benedict, C, Elmståhl, H, Brunstrom, JM, Hogenkamp, PS 2015 Are you sure? Confidence about the satiating capacity of a food affects subsequent food intake. Nutrients, vol 7 (7), pp. 5088-5097. Click here to view
- Brunstrom, JM, Rogers PJ, Myers KP, Holtzman JD 2015 In search of flavour-nutrient learning. A study of the Samburu pastoralists of North-Central Kenya. Appetite, vol 91, pp. 415-425. Click here to view
- Forde, CG, Almiron-Roig, E, Brunstrom, JM 2015 Expected Satiety: Application to weight management and understadning energy selection in humans. Current Obesity Reports, vol 4, pp. 131-140. Click here to view
Other coverage of our work:
- Hardman et al. article featured in the conversation - http://theconversation.com/how-eating-different-brands-of-the-same-food-could-be-encouraging-you-to-eat-more-42062
- Press release for Hardman et al. article - http://www.bristol.ac.uk/news/2015/april/food-brands-and-overconsumption.html
- This research has been featured in the BBSRC's Food Security News - http://www.bbsrc.ac.uk/news/food-security/2015/150317-f-how-do-we-choose-the-food-we-eat/