Recently I was away for a family vacation in the Adirondacks. For about 24 hours my diet consisted of beer, fudge from the Candy Cottage in Old Forge, and pizza. Also, I had the good fortune of being in the right place at the right time when a bag of marshmallows fell out of some persons truck. So, yea I had marshmallows too.

How I ate for those 24 hours was totally okay. I adjusted the next two days by making sure my diet was high in protein and vegetables and was lower in overall calories than normal.

Essentially, I had to inhibit the desire to eat as much as I normally do in order to prevent myself from gaining weight.

When a person inhibits an impulse to eat food that would undo their weight loss efforts or body composition goals they are expressing willpower.

It is clear that some form of restraint is necessary to achieve a weight loss goal or a specific body type. But this restraint is extremely challenging when we are surrounded by tempting food.

There is clearly some utility to resisting unhealthy food especially after indulging in a previous meal. Our problems occur when we consistently indulge and accumulate a positive energy balance meal after meal.

So why do we eat a lot of food and a lot of high calorie food meal after meal? Why don’t we adjust our intake?

I recently ran into some interesting research on how our Western diet can actually cause cognitive impairments that make inhibiting food impulses even more challenging.

I’m going to do my best to make this very readable but it is a little science heavy so if you want to stop reading, here is a funny cat picture so you don’t feel like you totally wasted your time

Brain Structures Affected by a Western Diet

Memory of past eating behavior can be a predictor of future food selection (Francis & Stevenson, 2013).

For example, if I had two cheeseburgers and fries for lunch I would use that memory and inhibit myself from eating a very large dinner.

The hippocampus is a structure in the brain that is important for learning and memory. When a person has a history of energy dysregulation (i.e. eat too much, eat too much high fat high sugar foods) signals to the hippocampus can be altered (Davidson 2007).

In their 2011 review of hippocampal dysfunction, obesity, and the Western diet, Kanoski and Davidson highlight the following:

* High saturated fat intake is associated with an increased risk of mild cognitive decline in learning and memory task.

*Simple carbohydrate meals can lead to poorer performance on memory task

* Excessive consumption of a Western diet can cause neurophysiological changes that impact the hippocampus causing impairments to learning and memory.

Vicious Cycle Model

Kanoski and Davidson (2011) proposed a ‘vicious cycle model’ where a Western diet that causes damage to the hippocampus can promote weight gain by interfering with the learned control of homeostatic eating.

The model suggests that eating a Western diet rich in high fat and high sugar foods and fluids may lead to brain pathologies which decreases a person’s ability to inhibit responding to food and food related environmental cues (Martin & Davidson, 2014).

The premise is that our ability to accurately recall what we had previously eaten is weakened by chronic consumption of these types of food.

Can Damage be Reverse?

 “It is unclear whether the impact on the hippocampus of consuming Western diet is reversible when the intake of the diet is discontinued or reduced.”

The majority of the research on hippocampal damage has been done with rodents and human studies are only just beginning which leaves the door open for many questions. Francis and Stevenson (2013) do note that it would be odd if the changes in brain structures seen in animals were also not seen in humans.

Brain derived neurotrophic factor (BDNF), a protein that aids in memory and learning, is reduced in the hippocampus when a high fat high sugar diet is consumed. Exercise is known to increase BDNF in the hippocampus, therefore, exercise may be useful to reverse damage (Francis & Stevenson, 2013).

Weight loss is a challenging process and based on the research presented it may be more challenging than most people think. Clinicians, personal trainers, dieticians, and other medical professionals should be sure to approach clients with compassion and patience when teaching them the skill sets necessary to live a healthy life.

Similarly, individuals attempting to lose weight should approach their own efforts with compassion, forgiving slip ups and understanding that the change process will not happen overnight.



 

 

References

Davidson TL, Kanoski S, Schier LA, Clegg DJ, Benoit SC. (2007). A potential role for the hippocampus in energy intake and body weight regulation. Curr Opin Pharmacol, 7(6): 613-616.

Francis H & Stevenson R. The longer-term impacts of Western diet on human cognition and the brain. Appetite, 63: 119-128.

Kanoski SE & Davidson TL. (2011). Western diet consumption and cognitive impairment: Links to hippocampal dysfunction and obesity. Physiol Behav, 103(1): 59-68.

Martin AA & Davidson TL. (2014). Human cognitive function and the obesogenic environment (2014). Physiol Behav 0, 185-193.