Sugar Cravings

Sugar Cravings

Adapted from the article "Junkie Food" by: Bijal Trivedi - NewScientist Magazine - 4 September 2010

Settled on the sofa watching the usual TV, you notice that predictable uncontrollable, nightly craving. At first you sit there fighting it. After 20 minutes, you can't fight any longer and you feel anxious and start fidgeting like crazy. Finally giving into your food addiction, you head to the freezer or cupboards for a fix. This could be ice cream or cookies or crackers or chips. Now you feel guilt. But what triggered such intense cravings? Do you lack will power? Or is something else driving your desire for certain foods.

There is more and more scientific evidence showing that certain foods are addictive. Sugar is the key ingredient in most junk food. Researchers studied rats given sugar syrup, similar to the sugar concentration in a typical soda beverage. After one month on this diet, the rats developed behaviour and brain changes that were identical to those or morphine-addicted rats. They binged on the syrup and showed anxious behaviour when it was removed – a sign of withdrawal. There were also changes in the neurotransmitters in the nucleus accumbens, a region associated with reward.

Crucially, the researchers noticed that despite having eaten it for weeks, the rats' brains released the neurotransmitter dopamine each time they binged on the sugar solution.
Dopamine drives the pursuit of pleasure - whether it is food, drugs or sex. It is a brain chemical vital for learning, memory, decision-making and sculpting the reward circuitry. As we eat more of this ‘sugary stuff', there is a dulling of the reward circuits, triggered by overuse of the drug (food). Thus, we need more of it to obtain a level of (dopamine) satisfaction. It's almost as though we have developed an immunity to the food and now have become "addicted”.

There may even be a genetic basis involving dopamine genes related to obesity and food addiction. In some obese people, it has been shown that the DRD2 and DRD4 genes have less active dopamine and as a result, have a dulled dopamine response when eating food that would normally be considered appetizing. The person must then eat more and it tends to be sugary foods, in order to get enough dopamine. This of course, is what leads to obesity.

Now that we know this, can we do anything about it? Presently no. However, people with these intense cravings should not feel guilty. The cause of their cravings may likely be a poor dopamine response to food.

We also know that exercise can raisedopamine levels. People who exercise on a regular basis, will have more impulse control when it comes to food. This might be a great reason for people to get out for a walk or get on their treadmill or bike or elliptical; if for no other reason than to raise dopamine sufficiently that cravings may be more readily controlled.

The more I read of the various gastro intestinal and brain hormones that drive us to eat , the more respect I have for people who are willing to ‘diet and exercise' to lose weight. It is not easy. We have many drugs to help us control blood pressure and diabetes and hypertension, yet we have a few hundred hormones driving us to eat. We expect people to get their weight under control on their own, when we have no drugs (yet) to help control cravings or change their metabolism.

I will stress again that weight loss and weight maintenance is a long frustrating journey. It takes a lot of will power, but overweight can be controlled. So, never give up. You can do it.

Dr Doug