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08 . 08 . 2018

The Neurobiology of Appetite - Part II

In the first part of this article we got to know the instinctive circuits that influence our eating behavior and often undermine weight loss goals. Why is it important to identify these unconscious processes that were reinforced throughout thousands of years of evolutionary pressures imposed on the human species?

Despite having been crucial for the preservation of the species, the mechanisms that lead us to search for and accumulate calories are no longer aligned with the world we live on, where there is abundance of processed foods at our disposal at any time. In order to lessen this imbalance, the idea is to consciously alter the information that reaches our instinctive brain so that the final result meets the desired goals.

The success of the obesity battle will, inevitably, require global public health measures that difficult the access of the population to highly processed foods, specially “designed” to escape the appetite regulating systems and make us overeat. Measures like the taxation of certain food items, advertising restrictions and investing in education, specially targeted at the younger generations, seem like logical interventions.

 

In order to lessen this imbalance, the idea is to consciously alter the information that reaches our instinctive brain so that the final result meets the desired goals.”

 

Here we will focus on an individual perspective. What can each of us do to promote a healthier eating behavior that leads to weight loss?

  • Create a healthy food environment – if we are surrounded by food that stimulates our impulses to overeat, it will be harder to control them. Hence we should remove these type of foods (cookies, ice cream, candy, chocolate, sweets, etc.) from our home and work environments. Ideally, the available food should not be visible and require some work to be eaten, like a piece of fruit that needs to be peeled or some other item that needs to be cooked. The strategy here is not to send a message of food abundance in the environment to our brain.
  • Control our appetite – if the brain “thinks” we are starving,  it will activate the circuits that increase calorie ingestion and, probably, overcome our willpower. To neutralize this message, one should eat foods that are more efficient at inducing satiety. By default, the most satiating foods have the following properties: low calorie density (less calories delivered by a unit of volume), high fiber and/or protein content, moderate palatability (the tastier a food is, the more we can eat before we feel satisfied). From a practical standpoint, a satiating diet is composed by simple foods, as close as possible to their natural state, like fresh meats and fish, eggs, vegetables, fruit, root vegetables and whole grains (avoid bread, including whole grain variety, as it is surprisingly calorie dense. Prefer oatmeal, for instance).

 

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White potatoes are one of the most satiating foods.

 

  • Keep meals relatively simple – limiting each meal to 3-4 different foods helps reducing calorie ingestion because our satiety receptors are taste specific, and if we try several flavors, at the same meal, we tend to overeat (this is called the buffet effect). If we must have dessert, every now and then, fruit is the best option.
  • Pay attention to food reward – as we’ve seen our brain values calorie dense foods that have combinations of fat, sugar, protein and salt. When we eat these foods, dopamine is released in specific areas of the brain and that can result in an addictive behavior. We should be very cautious about these highly rewarding foods, to which our ancestors never had access to in Nature. All of us should identify our food addictions and avoid their consumption.
  • Do not add extra calories to addictive substances   substances like caffeine, alcohol and theobromine (found in chocolate) are naturally stimulating and their consumption directly activates the reward circuits. If we associate calories to these stimulants, we are enhancing the addictive potential. Therefore stimulants should never be combined with fats and sugars, if our goal is to lose weight.
  • Maintain a stable meal schedule and avoid snacks – eating at the same time consistently helps stabilizing our circadian rhythm and optimizing digestion. Except for people with blood sugar problems (diabetes and hypoglycemia), three meals a day are sufficient to ensure proper nutrition. Snacking between meals increases the amount of calories consumed, and shouldn’t be encouraged.
  • Make sleep a priority – the quantity and quality of our sleep are determining factors in adiposity control. There is evidence that sleep deprivation leads to an overall increase of calorie intake and specific cravings for calorie dense foods. The ideal sleep duration varies among individuals (somewhere between 7-9 hours), but it should be restorative and in agreement with the circadian rhythm.

 

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Good sleep is key to maintaining a healthy weight, like it is for many other physiologic functions.

 

  • Regular physical activity – there are two ways through which physical activity promotes weight loss: first and foremost by increasing calorie expenditure and, in the long run, by maintaining the lipostat set to a lower body fat level. Evolutionarily speaking, our sedentary lifestyle is completely foreign and should be strongly opposed. Diverse activities like walking, jogging, swimming, biking, strength training, among many others, are encouraged, if possibly daily. Something as simple as walking or biking to and from work, can make a huge difference in weight loss.
  • Minimizing the effects of stress – many of us are subject to several stressors in our daily lives, and not all of us find ways of preventing their deleterious effects on health, including weight gain. Practices like meditation, Yoga or Tai Chi are valuable tools to help mitigating the effects of stress on our lives. It is also important to identify certain ruminating thought patterns that don’t serve us, and try to reframe them. Lastly, we should remove highly rewarding foods from our environment as these are the ones we tend to reach for in stressful situations.

We are all unique, including our neurology and biochemistry, and for this reason each of us will need specific lifestyle adjustments. Nevertheless, I hope to have passed on the message that weight loss is a more complex topic than sometimes advertised, involving deeply hardwired unconscious mechanisms that the human brain “learnt” throughout thousands of years to keep the species alive. The good news is that we can now use these insights into brain neurochemistry to delineate strategies to align our unconscious impulses with the goal of reaching and maintaining a healthy weight.

 

References:

Guyenet, SJ. The hungry brain : outsmarting the instincts that make us overeat. Flatiron Books, 2017.

Whiten, A. Forever Fat Loss: Escape the Low Calorie and Low Carb Diet Traps and Achieve Effortless and Permanent Fat Loss by Working with Your Biology Instead of Against It. Archangel Ink, 2014

Lutter, Michael, and Eric J. Nestler. Homeostatic and Hedonic Signals Interact in the Regulation of Food Intake. The Journal of Nutrition 139.3 (2009): 629–632.

Categories: Exercise, Nutrition, Obesity

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