Posted on September 30 2018
Aside from our taste buds, our brains may have a lot to do with our preference for highly processed, less healthy foods, and this link may be difficult to manage and control.
The digestive system in all animals signals the brain when it encounters a carbohydrate or a fatty food, and the brain's job is to estimate how much energy the food contains and to guide the animal to eat a certain amount, based upon survival needs. As our systems developed over our evolutionary lifetime, these signals were typically "pure" in the sense that they were triggered by the consumption of one type of food at a time. Either meat (a fatty food) was being consumed, or nuts (fatty) were being consumed, or fruits (carbohydrates) were being consumed. Combinations of different types of food are rarely found together in the wild.
However, processed foods tend to be high in both fat and carbohydrates, a combination that the brain is not used to seeing (in evolutionary history). Yale psychologist Dana Small decided to try to determine if this combination had a particular effect on the brain using MRI brain scanning techniques. He had people eat samples of cheese (high in fat), lollipops (high in carbohydrates) or cake (high in both) designing the samples so that they were identical in terms of their energy content. Presumably the brain would be equally responsive to each type of food because their energy contents were identical.
What he discovered was that the brain's "reward circuits" were most active in response to consuming the cake. He hypothesizes that the brain has not evolved to correctly assess the energy content of a food high in both fat and carbohydrates because that combination was rare in our evolutionary development. And, he suggests, this connection between food high in both fat and carbohydrate and our brain's response is "unconscious" and therefore, very hard to modulate based upon knowing that a food, like cake, is not good for you. These highly processed foods are not only engineered to taste good, they also appear to have the ability to trigger a response in our brain that drives us to consume them, even knowing they are not good for us.
Donut, anyone?
So, what can we do to improve our healthy eating habits in the face of this surprising brain challenge? One thing would be to try to reduce or eliminate highly processed foods from our diet, which we know we will consume too much of because of our brain's response to them. Eat more like our evolutionary ancestors: simple foods, not complex and highly processed foods which are likely to stimulate brain signals to eat more than we should.
The digestive system in all animals signals the brain when it encounters a carbohydrate or a fatty food, and the brain's job is to estimate how much energy the food contains and to guide the animal to eat a certain amount, based upon survival needs. As our systems developed over our evolutionary lifetime, these signals were typically "pure" in the sense that they were triggered by the consumption of one type of food at a time. Either meat (a fatty food) was being consumed, or nuts (fatty) were being consumed, or fruits (carbohydrates) were being consumed. Combinations of different types of food are rarely found together in the wild.
However, processed foods tend to be high in both fat and carbohydrates, a combination that the brain is not used to seeing (in evolutionary history). Yale psychologist Dana Small decided to try to determine if this combination had a particular effect on the brain using MRI brain scanning techniques. He had people eat samples of cheese (high in fat), lollipops (high in carbohydrates) or cake (high in both) designing the samples so that they were identical in terms of their energy content. Presumably the brain would be equally responsive to each type of food because their energy contents were identical.
What he discovered was that the brain's "reward circuits" were most active in response to consuming the cake. He hypothesizes that the brain has not evolved to correctly assess the energy content of a food high in both fat and carbohydrates because that combination was rare in our evolutionary development. And, he suggests, this connection between food high in both fat and carbohydrate and our brain's response is "unconscious" and therefore, very hard to modulate based upon knowing that a food, like cake, is not good for you. These highly processed foods are not only engineered to taste good, they also appear to have the ability to trigger a response in our brain that drives us to consume them, even knowing they are not good for us.
Donut, anyone?
So, what can we do to improve our healthy eating habits in the face of this surprising brain challenge? One thing would be to try to reduce or eliminate highly processed foods from our diet, which we know we will consume too much of because of our brain's response to them. Eat more like our evolutionary ancestors: simple foods, not complex and highly processed foods which are likely to stimulate brain signals to eat more than we should.
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