Research & Education

Fighting DNA: The Role of Genetics in Food Preference and Weight Management

It's that time again: the start of a new year when many patient's concerns turn to losing the weight they put on during the holidays. It's no secret that staying away from one's favorite foods is a tall order. But besides the obvious factors inexpensiveness easy access social reinforcement that make refined carbohydrates and foods made with cheap vegetable oils so easy to overconsume there's another less obvious obstacle that presents an additional layer of difficulty: the sense of taste itself. 

From an evolutionary perspective fat and simple carbohydrates were both extremely valuable nutrients. Gram for gram fat provides over twice the energy of carbohydrate or protein so the ability to perceive the presence of fat through sensory channels may have offered a kind of survival advantage in environments where constant access to abundant food was not guaranteed. And simple carbs provide a burst of quick energy a good thing when you might have to outrun a predator. In the modern world however where large amounts of all three macronutrients are no further away than a drive to the grocery store these sensory strengths can contribute to body fat gain and other health problems. 

One study showed that subjects determined to be hypersensitive to the presence of fatty acids in foods had habitually lower fat and total energy intake. This is supported by a similar study which demonstrated that people with an inability to detect low concentrations of fats in foods were more likely to consume greater amounts of fatty foods and to have higher BMIs. Taken together these studies suggest that perception of a foods composition in the mouth may influence how much of that food is consumed before it even gets digested and has a chance to more fully influence physiological and psychological behavior concerning food intake. These studies also employed food journals and food habit questionnaires the latter of which are notoriously problematic for the purpose of obtaining definitive data. Nevertheless the conclusions do provide something worth considering. Perhaps some people's increased consumption of low-fat foods isn't due only to the additional sugar that is typically present but also to a hard-wired mechanism seeking more fat. (The less fat present in a food the more of it one would be driven to consume.) 

Another study suggested that perceived taste intensity might influence changes to body weight and other health markers. Subjects had differing intensity perceptions for sweet salty sour and bitter flavors but overall the data indicated that compared to subjects with taste intensity perceptions aligned with population averages subjects with above-average perception for all tastes tended to have larger increases in body mass waist circumference and hemoglobin A1c over a five-year follow-up period. The groups with the highest intensity perceptions reported larger hedonic associations with strawberries sweets salted pretzels milk chocolate mayonnaise and sausage. Perhaps what leads people to consume larger amounts of certain foods isn't the taste per se but rather the perception of flavors and the amount of pleasure or satisfaction an individual feels upon consuming the food. This is likely why some weight loss experts suggest consuming bland foods and avoiding foods that are considered rewarding such as those that combine multiple flavors and textures not found in natural whole foods.

What's at the heart of someone's taste intensity perception might be genetics. There are myriad variations in genes associated with taste receptors making some people more sensitive to certain flavors than others. There are supertaster's medium taster and non-tasters for bitter flavors and likely for the other flavors as well. These genetic variations might lead to different preferences for sweet fatty or salty foods. One study showed taster perception to be associated with BMI in women: non-tasters had a higher BMI than medium and supertasters. Supertasters might have an aversion to foods they are highly sensitive to while non-tasters might consume more because the flavor perception does not register as readily. Of course genotype wasn't the only correlative factor in food intake. The study authors concluded that environmental factors and sociocultural conditioning can outweigh genetics.

As for children who don't want to eat their vegetables there could be a genetic reason for fussiness at the dinner table. Greater sensitivity to bitter flavors (such as those in dark leafy greens) predicts a lower preference for vegetables in children. Adding a little cheese or salad dressing just might incline a child to eat their veggies with less protest.

 

 

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