Health - Research - Simplified

Addicted to fast food?

In Addiction, Body weight on January 21, 2011 at 15:09

The other day, I read an interesting article regarding food addictions. Within this article, the author mentioned a study regarding fast food and calorie consumption that caught my attention. The purpose of the study was to see how eating fast food was related to how much food was consumed and how it could potentially be the result of a food addiction.

The researchers recruited 54 adolescents who ate fast food at least once per week. For the first part of the study, they took the adolescents to a local food court and gave everyone the same fast food meal. They could eat as little or as much as they liked, and were told that more food was available if needed. When the participants were nearly finished of their meal, the researchers filled trays in the center of the table with more food and drinks so as to ensure they were able to eat as much as they liked. After the meal, the participants had to estimated the size of the meal they just ate by comparing it to normal fast food meals they usually eat (bigger or smaller). The calories they ate were then calculated by the researchers. During the second part of the study, the researchers collected dietary data from the same adolescents where they had to write down what they ate for 4 days – 2 days where they didn’t eat fast food and 2 days in which they did.

What did they find? At the food court, the participants ate an average of 1652 calories – 61.6% of what they should eat in one day. To put this into perspective, if someone eats 3 meals per day and a couple of snacks, each meal should not exceed 30% of their total daily calories (in this group that would mean 790 calories) – so basically, on average, all the adolescents ate two times what they should have eaten during their fast food meal.  Further analyses showed that the overweight adolescents ate more, both overall and relative to their body weight, than the lean adolescents yet their meal size ratings were the same. This means that the overweight kids either eat this much on a regular basis or didn’t realize how much they actually ate – either situation being less than ideal.

During the second part, they analysed how much the adolescents ate on a “fast-food” day compared to a “non fast-food” day. They found that the overweight adolescents ate 400 more calories per day on the days they ate at either McDonald’s, KFC, Burger King, Wendy’s or Taco Bell whereas the lean adolescents ate the same, regardless if they ate fast food or not. This means that when overweight individuals eat a meal really high in calories, they do not compensate for the large intake for the rest of the day (i.e. they do not have a smaller supper).

The authors of this study made an interesting point stating that it would be impossible to overeat to such an extent as the adolescents did at the food court if the food was of higher quality (more fiber, more satiating (made you feel fuller), food that you had to chew more etc.). “Fast food” can have two interpretations – food that you can get fast and food that you can eat fast. But, if it was just the low quality of food that permitted overeating, then why didn’t the lean adolescents eat as much as the overweight adolescents at the food court and why did they compensate for the fast food meal by eating less during the rest of the day?

Putting these two studies together reveals something interesting:

overweight individuals, unlike lean individuals, may not have the same ability to regulate their food intake or their brain is not as efficient at registering how much they have eaten.  And here is where I refer back to the initial article that introduced me to this study. In his article, Dr. Hyman said that the overweight individuals ate more because the addiction centers of the brain responded to the sugar, fat and salt in the meal, initializing their reward system (similar to the “reward” feeling of a drug or alcohol to a drug addict or an alcoholic) making them unable to stop eating.

The scientific article does not say anything about the children being addicted to the food, but it could be a theory as to why the overweight children at more.  Researchers are learning that these reward systems are different in individuals with weight problems.  It is unknown whether it is the weight surplus that reduces one’s ability to gauge the amount of calories eaten or if people are born this way, which then leads to weight gain due to their excessive eating, but research is leaning towards the latter.  Recently, a research group found that those with an increased waist circumference had more a specific gene that is also related to drug addiction (Heard-Costa, 2009).

I decided to do a little research on food addiction, similar as to what Dr. Hyman put in his article, and I found some interesting findings to add to his list (Grigson, 2002):

  • Eating sweets can release opiates (like morphine) in the brain, and opiates in turn, increase the palatability (taste) of food.
  • The liking for drugs and alcohol are related to the liking for sweets.
  • Restricting food increases cravings (why diets usually only work in the short-term) – sort of like a smoker without any smokes. Not only that, but if you had ever eaten something sweet when you were really hungry, you were more likely to crave that food when you are hungry again.
  • Cravings are the primary cause for relapse in addiction and cravings of certain foods increase when in the presence (or even when just thinking about) food. In our current environment, we are bombarded by images, smells, and talk of food – makes sense.
  • Repeated exposure to “natural rewards” (i.e. frequent eating of sweet or fatty foods) may lead to addictive-like responses – increased sensitization – to that food where the more you eat it, the better it makes you feel (until afterwards…).

My thoughts: Firstly, this study emphasizes that fast food can be detrimental to one’s health. They are low quality, calorie-dense foods that play with our brain perceptions of satiety (fullness). Although this was just shown mostly in overweight adolescents, I would recommend limiting fast food intake in anyone as the lean adolescents still overate. Secondly, poor diet and reduced physical activity are known to be related to obesity and play a large role in maintaining an energy equilibrium, but the real cause of excessive weight gain is more complex. It is known that obesity is more to do with brain physiology than will power and we should really start thinking of it this way. Because of this, behaviour therapy treatment can be an addition to a healthy eating regimen and a physical activity program to increase the odds of weight loss success. Somehow we need to break the train of thought between cravings/false hunger and eating, and slowing down the pace of eating cannot hurt.  All this addiction talk makes sense though – we are animals, programmed to survive and to survive we need to eat, drink, protect ourselves and procreate. All these things feel pretty good, no?


Ebbing et al., 2004. Compensation for Energy Intake From Fast Food Among Overweight and Lean Adolescents. JAMA; 291(23).

Heard-Costa et al., 2009. NRXN3 is a novel locus for waist circumference: a genome-wide association study from the CHARGE Consortium. PLoS Genetics. 5(6).

Hyman, M. Oct. 16. 2010. Food Addiction: Could It Explain Why 70 Percent of Americans Are Fat? The Huffington Post.



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