Evidence suggests that both fat and sugar are able to stimulate the dopamine reward pathways of the brain which acts to reinforce the behaviour of future consumption. Therefore fat and sugar have the potential for addiction in those that eat them in high amounts. In sensitive individuals, stimulation of the reward centres of the brain may lead to overeating of fat and sugar and this in turn creates the metabolic conditions for binge eating. Binge eating currently affect around one third of the population of the United States, and this type of eating behaviour is linked to anxiety, depression and other brain changes that may signify addition. However, while fats and sugars do share similarities in stimulation of neuronal pathways (e.g. activation of the mesolimbic dopamine system), there are clear differences between their addictive patterns that suggests dissimilar neurochemical activation.
When rats are fed a sugary drink intermittently, they increase their sugar consumption dramatically and consume large amounts of sugar whenever it is offered to them. In contrast, rats that have constant access to the sugar also increase their sugar consumption, but they do not binge like the restricted rats. However, in both these groups the rats have similar body weights to normal rats suggesting that rats are able to compensate for the extra energy by decreasing other foods or by increasing energy expenditure. Rats given restricted access to fats also binge on the foods, but like the sugar binging rats, do not gain weight. However, when fat and sugar mixtures in the form of cookies are presented to rats intermittently, they binge and gain weight. This suggests that sugar and fat are required in combination (at least in rats) in order to gain weight from binging.
The palatability of high fat and high sugar foods increases the chance that they will be consumed in large quantities. This is especially true in Western nations where these foods have become widely available. This palatability stems from their effects on the brain, effects that are not seen with many foods considered bland such as vegetables, fruit and protein. Researchers have highlighted similarities between food binging and drug addiction. This research is based upon imaging scans of the brain that show similar patterns between drug addiction and sugar cravings. Rats that have been binging on sugar show signs of withdrawal similar to drug addiction when access to the food is removed. Rodents allowed access to high sugar foods for a number of weeks will endure harsh environmental conditions to attain the same foods. However, it appears that only sugar causes the brain changes necessary to cause withdrawal symptoms, as rodents fed fat maintain normal brain patterns.
RdB
