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Wednesday, November 21, 2012

Some Science Behind Snacking

Today I'm excited to have my daughter Kiersten's boyfriend Julian join us on the blog. Julian is currently a M.D Candidate at the prestigious Cleveland Clinic Lerner College of Medicine, and recently received his Masters in Neuroscience from Queen's University - my old stomping grounds too! Julian will share Some Science Behind Snacking... Just in time for the holiday season might I add ;) Take it away Julian. 

Julian snacking and studying at his favorite library!


This Sunday, not unlike other Sundays, I will sit down at my desk for my 8 or so hours of obligatory studying. During this stint I will probably make 8 or so trips into the kitchen to hunt for snacks. Chips are the usual culprits, but snow peas, nuts and seeds become very popular when Kiersten visits.

Looking for an excuse for my constant snacking I headed to the internet, straight to PubMed, to find some scientific explanation (especially one that does not implicate “poor self control” as a cause for my habit). I was reassured by a paper that showed a link between a heightened sensitivity of mouth, lip and tongue to overeating. The paper went on to explain why this heightened sensitivity would make eating particularly “rewarding” to the individual. Now I had my excuse. Curses to my overly sensitive mouth!



Sometimes it is comforting to find a reason for bad habits that is out of our control- some sort of irregularity in our genes that makes us act a certain way. It gives us an excuse for continuing these bad habits. You do not need to be a Neuroscientist to understand that obesity is NOT caused by highly sensitive mouths, lips and tongues. Sure, it may contribute, but it is dangerous to put a lot of stock into some of these findings.

Let me contradict myself for a second. There are some cases when irregularities in our genes DIRECTLY contribute to overeating. As an example, our body has “stop” and “go” signals for eating. Leptin is the “stop” signal. It is a hormone secreted by our fat cells and when we consume fatty food, it is released, travels to the brain, and tells us to stop eating. Some obese individuals have a genetic mutation that reduces leptin production, preventing them from regulating food intake in response to increased body fat. Individuals with leptin deficiency have stronger than normal appetites and feel hungry much of the time. For them, overeating is not primarily related to pleasure and reward, but is a response to inaccurate hunger cues.

Similarly, you can have irregularities in the “go” signal for feeding. Ghrelin, recently discovered, is the “go” signal that is released from the stomach, travels to the brain, and stimulates appetite. Ghrelin levels are high when the stomach is empty and decline following meals. Obese individuals show abnormally high concentrations of ghrelin- a constant “go” signal, which may underlie their dramatic overeating and weight gain.

So where can we assert blame for our constant-snacking or overeating? Is it in our genes? Is it our own lack of self-control? Probably the best answer lies in-between. Vulnerability to overeating and obesity is at least partially encoded in our genes. Yet, our environment and our goals play an essential role. Let me elaborate on the latter two factors.

In considering our environment, there is evidence that the quantity of food consumed on average has not increased as much as the dramatic rise in obesity rates. This may seem odd when you look at the portion sizes at Denny’s or at The Cheesecake Factory. But indeed the spectacular rise in obesity may have more to do with the changes in the nutritional content of diets and the decline in physical activity, than the actual portions that people consume. Thus, the sedentary, nutritionally-questionable lifestyle may be one of the most serious threats to our health. This problem is compounded by the fact that our brains have difficultly telling us that what we are doing is bad for us. From an evolutionary perspective, overeating is an adaptive behavior that promotes survival and reproduction by replenishing our energy stores whenever available. Furthermore, the part of your brain that controls reward and pleasure is readily activated by feeding.

So this is where YOU come in. Your goals play an essential role in your ability to control your eating habits. Sometimes we cannot rely on our body and brain to do the right thing for us. We may have a genetic vulnerability to overeat and our brains have a hard time telling us which foods are good and which foods are bad. If your goal is to be healthy and to have a higher level of energy and function, then this may be the most powerful stimulus to quell your bad eating habits.

I can only blame my sensitive mouth so much for my constant snacking. Eventually, it will be up to me to follow my own goals in being healthy and controlling my behavior. Yes, those chips are delicious and salty and the primitive part of my brain is telling me they are good for me. But my brain is more than its primitive part. It is aware of the detriments of overeating and onslaught of problems I will cause myself by eating nutritionally-questionable foods. Just as bad habits become “hard-wired” in our brains, so can good-habits and it is the conscious and repetitive behavior of these good habits that will inevitably replace those bad-habits. I guess replacing the chips with Kiersten’s snow peas is the first step. I’ve got to head to the store.

-Julian deBacker
B.Sc., M.Sc., Queen’s University
M.D. Candidate, Cleveland Clinic Lerner College of Medicine

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