Is there a link between addiction and obesity?

Hi again. Dr. Heinzerling from UCLA SARx here. Today's topic is another one that patients frequently bring up: "Is there a link between addiction and obesity?" In other words, are people obese because they are addicted to food or to eating? A recent study from Dr. Ashley Gearhardt and colleagues at Yale provides some interesting insights into this hypothesis, even if it does not completely answer the question. The study looked at areas of brain activation using functional MRI among a sample of young women. The women were recruited for the study from a program developed to help people "achieve and maintain a healthy weight on a long-term basis." Interestingly, not all of the women were obese (or even overweight) on the basis of BMI, which is the body mass index (weight in kilograms divided by height in meters squared). The average BMI was 28 (BMI of 25-30 is overweight and BMI of 30 and above is obese) and the lowest BMI was 23.8 (normal range).

The women were assessed for possible symptoms of "food addiction" using the Yale Food Addiction Scale (YFAS), which is a series of questions that apply the symptoms of drug addiction to food. In short, the YFAS measures how much compulsive behavior there is around food. The women did not eat for 6 hours so they were hungry and then underwent an MRI scan during which they were shown a picture of a milkshake or a glass of water. The MRI measured brain activation while they were anticipating having the milkshake or glass of water. Then they actually got a taste of the milkshake or glass of water (which was actually a clear liquid designed to mimic saliva) and the MRI measured brain activation again.

The results are that the womens' scores on the food addiction scale when anticipating food correlated with activation in brain areas that are the same ones that are activated when a person addicted to drugs is shown a picture of the drug and experiences cravings. Also like the case in drug addiction, women with high food addiction scores, also had reduced brain activation in an area of the brain thought to be important in self-control (the lateral orbitofrontal cortex) suggesting that they may have less ability to resist eating due to this.

The study suggests that similar brain processes may be happening in people with symptoms of "food addiction" as occur in persons with drug addiction. The interesting part is that you cannot say that this pattern of brain activation is associated with OBESITY per se, as not all of the women with high "food addiction" scores were obese, possibly due to compensating in other ways (exercise, dieting) for their drive to overeat. This makes a similar point to one that we often make to patients entering treatment for drug or alcohol addiction: medications can help with addiction but they are not a substitute for trying hard and establishing an environment that supports avoiding drug/alcohol use. The authors of this paper point out that their study suggests that the brain of people with "food addiction" symptoms seems to react strongly in response to cues for eating (seeing the picutre of the milkshake) and that this may make them particularly prone to food cues in the environment such as advertisements for fast food, etc. As a result, controlling over-eating may require limiting exposure of people to these cues.

A very interesing study that provides insights into neurobiology and society! As always let us know what you think via our twitter feed (@UCLASARx) and see you next time!