Hormones, Chemicals, and Weight

We hear it said all of the time "eat less, exercise more" to lose weight. If it were that simple, why would 1 in 4 Canadians be considered 'obese'? 

Hormones have a significant impact on our appetite and, as a result, how much food we consume in a day. Three of the hormones and chemicals that play a important role in what, when, and how much we eat are:


Leptin is a hormone that is produced strictly by fat cells in the body. When leptin is produced, a message is sent to the brain that we do not need of anymore fuel. 


Insulin is produced by cells in the pancreas called the beta cells and is then transported directly to the brain. Insulin is produced after we eat foods containing carbohydrates. It is responsible for getting the sugar circulating in the blood where it belongs. 


Also referred to as the "reward neurotransmitter". It is the release of dopamine that we "crave" when we decide to indulge in highly palatable foods (think: chocolate, chips, cookies, etc.). 


When we consume highly palatable foods, we activate the "reward circuitry" within the brain and dopamine is released. This gives us a quick rush of good feelings. 

Once consumed, both food and drugs light up the same pathway in the brain, eventually reaching the brain's pleasure centre, which then sends out a message to "consume more".

This reward circuitry doesn't only occur in humans. Studies have shown that well-fed rats, with food freely available, will voluntarily expose themselves to adverse conditions (ex. extreme cold, foot-shocks, heat pain) in order to obtain highly palatable foods (shortcake, Coca-Cola, M&Ms, chocolate, etc.). So what does this mean? We will go to long lengths to activate that reward circuitry in the brain. If that wasn't bad enough, food restriction/deprivation increases the reinforcement value of a highly palatable food. As a result, avoiding the dish filled with our favourite candies at work gets harder every day that we diet. 

So with this drive to adhere to the "eat less" portion of the weight loss equation, why do we continue to overeat? 

Well.. there are three hypotheses:

  1. Down-regulation of reward: Consistently overindulging in highly palatable foods causes adaptive changes to occur within our brains - meaning we need MORE of the highly palatable food to produce the same dopamine response we used to get after consuming only a small portion of the same food. Lets use cookies for example: one cookie after supper results in a dopamine response that makes you feel great. Unfortunately, after three weeks of consistently having that one cookie after supper you find that you're reaching back into the cookie jar for a second cookie in order to get that same feel good sensation.
  2. Leptin and Insulin resistance: Both leptin and insulin signal to the body that we have eaten and our body is not in need of any more fuel (food). If we become resistant to leptin and insulin, either because there is reduced transport of these chemicals to the brain or because we are becoming desensitized to them, our appetite does not get turned off. As a result - we are always hungry! Definitely not ideal when we are trying to lose or maintain our weight. 
  3. Gluttony hypothesis: Finally, this hypothesis states that we tend to overeat highly palatable foods simply because doing so results in a release of dopamine (the feel good neurotransmitter in the brain) and that makes us feel good! 

If you find yourself succumbing to the temptation of various indulgent foods, there are a number of things you can do to help end the cycle:

  1. Choose healthy fixes that give your brain a natural boost of dopamine. These healthy fixes do not necessarily have to be foods - they can be physical activity or positive social interactions. For example, next time you're tempted to indulge in some late-night snacking, instead engage in an activity that you enjoy (reading, taking a bath, playing with the dog, watching reality TV, etc.).
  2. Recognize that you will experience "withdrawal" symptoms from these indulgent foods. Eliminating sugar and processed food from your diet will likely result in an uncomfortable 2-5 days before the physical cravings for these foods subside. Enlist as much support as you can during this time and make time for as much rest and relaxation as you can (although, some people find it easier when they are busy doing something they enjoy, like shopping).
  3. Know that your taste preferences will eventually change. The best example I use with my clients is carrots. When we are consistently indulging in highly palatable foods, carrots are often considered a bland-tasting vegetable. Once we significantly reduce our intake of these highly palatable foods, carrots begin to taste much sweeter and we tend to enjoy them much more! 
  4. Get sufficient quality sleep each night. Not getting enough equality sleep fuels overeating. When we're tired, we tend to reach for high sugar foods that will give us a temporary boost of energy.
  5. Work on stress management techniques. This can be whatever works best for you - meditation, exercising, watching a movie, etc.
  6. Drink lots of water. Our bodies often mistake hunger for thirst and therefore, not drinking enough water can lead to overeating. Start your day with 16 ounces of room temperature water with the juice of half of a lemon and you'll be off to a great start!
  7. Reconnect with food through intuitive/mindful eating. Before each meal or snack, rate your hunger on a scale of 1 to 10 - 1 meaning your stomach growling, blood sugar low, "hangry" and 10 meaning you're stuffed and could not eat another bite if you tried. This rating scale will allow you to get better in tune with your hunger and, as a result, you will begin to make better food decisions. 
  8. Shop smart! Make a list and shop the perimeter of the grocery store. If the tempting foods are not in your house, you will think about and consume them much less frequently! 

The next time you have one of those pesky cravings give some of the above methods a try and let me know how you make out!


Yours in health,


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The contents of this website are for informational purposes only. It is not intended to offer personal medical advice, diagnose health problems or for treatment purposes. It is not a substitute for medical advice provided by a licensed and qualified health professional.
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