Is our diet in harmony with our cerebral health? Over the years, we have seen fad diets come and go. Do they really undo years of abusive eating patterns? Are they sustainable enough to fit into our lifestyle? Anorexia, bulimia, over eating – these are all different forms of eating disorders.
The world has undoubtedly seen a massive spike in obesity in the last 30 years. One of the leading contributors is a diet consistently high in saturated fats and sucrose.
Obesity and its impact on brain health
More than 500 million people worldwide are affected by obesity. In 2014 itself, Time magazine reported that obesity cost global healthcare services an estimated USD2 trillion annually. This was more than the cumulative costs of war and terrorism, it said. This mammoth figure corresponded to 2.8 percent of global GDP. Most of us are aware of obesity as a risk factor for diabetes, heart disease, musculoskeletal disorders. However, there is now growing concern over its impact on cerebral health.
Let’s try and explore the causal relationship between eating disorders (mainly from saturated fatty acids and free sugars) and brain health. To understand how eating behaviour can impact brain mechanisms, it is important to look at the regions of the brain that play a key role in eating behaviour.
The lateral hypothalamic area (LHA) controls our physiological functions. The LHA neurons have a gene level association with human body mass index (BMI). A diet consistently high in saturated fatty acids (SFA) and free sugars may alter genetic expression associated with neuronal activity. Not only do LHA neurons control satiety, they also become less responsive to high concentrations of SFA and sucrose. The chronic modification of these neurons through such prolonged exposures eventually hinders neural activity. Simply stated, hypothalamic damage weakens the brakes on feeding and promotes overeating and obesity.
How our brain responds to hunger and satiety
The hippocampus, located in the medial region of the temporal lobe, is a part of the mesolimbic system. It is associated with working memory, episodic memory (what we’ve eaten) and our response to hunger and satiety. It receives inputs from neurotransmitters like dopamine, serotonin and norepinephrine. And it works with the amygdala – the almond shaped structures. There is one located in each hemisphere to process our emotions and translate them into definitive outcomes. This region is vulnerable to a busy traffic of pro inflammatory cytokines that trigger inflammation within the body.
The hippocampus regulates food intake via several interconnected pathways, sometimes referred to as the ‘reward pathway’ or the ‘dopamine axis’. Several food related processes take place in what is called the ‘hippocampal amygdala circuit’ such as hunger and thirst signals, craving and imagery of food and nutrient learning and flavour exposure. The hippocampus also controls our responses to when, what and how much to eat, and our bodies’ adrenal stress that leads to stress eating.
Hippocampal atrophy may be attributed to certain foods
Studies have shown a correlation between BMI and hippocampal volume. Pro inflammatory cytokines within this region play a potent role in neurodegeneration. These cytokines are produced by the adipose tissue. Thus, a higher body fat percentage is linked to lower hippocampal volume. Hippocampal atrophy can be caused by and may further promote the consumption of a diet high in SFA and sucrose. This is how the vicious cycle of emotional eating, and overeating begins. It may manifest even before obesity finally sets in.
Obesity does not set in overnight. It results from many causes ranging from stress to faulty diet choices. It is one of the outcomes of the many eating disorders we know of. These eating disorders result from and cause hypothalamic damage, hippocampal atrophy and amygdala hijack, where neuronal activity and plasticity of the brain is altered.
Nutrition over numbers
This diet induced cognitive deficits need to be countered with a transition from processed to natural foods. That will need correct nutrition counselling and awareness. It is possible to overcome these disorders and enjoy optimal weight, without jeopardising one’s health. So if you’re looking for long term success, focus on the quality of your foods, especially ones that give you more nutrition per calorie.