By Graham Beaton

We are constantly hearing that the number of overweight and obese individuals is rising. The latest estimates suggest that 59% of Canadian adults are overweight and 25% of Canadian adults are obese. This trend for increasing weight gain among Canadians has had, and will continue to have, a dramatic impact on health care costs since being overweight or obese increases one’s risk of developing several chronic diseases. Specifically, increased weight can lead to cardiovascular disease, type 2 diabetes, certain cancers, liver and gallbladder disease, sleep apnea, respiratory problems, osteoarthritis, and mental health concerns such as anxiety and depression.

This article will discuss why being overweight or obese increases the risk of certain diseases and evidence that suggests that weight can influence mood and food choices.

Obesity and the altered function of fat cells
Fat cells (called adipocytes) have several functions. Firstly, they serve as energy stores. They can also influence the amount of food consumed and stored, inflammation, and various metabolic functions through the production and release of various proteins.

Adipocytes in obese individuals behave differently than adipocytes in non-obese individuals. Normally, adipocytes regulate the release of fatty acids when energy is required. In obese individuals, this regulation can be lost, and fatty acid concentrations increase, increasing cardiovascular disease risk1. Moreover, in many overweight and obese individuals, the function of adipocytes is further altered to release proteins that promote inflammation1-2. Normally, inflammation is a function of the immune system that allows our bodies to fight infections and to breakdown and repair cells and tissues of the body. This function is controlled and limited to the time required to make repairs. But, in overweight and obese individuals, the control is lost and there is often a low level of inflammatory cells that remain in the body. These cells may end up targeting healthy cells, which can increase risk of developing certain conditions (cardiovascular disease, arthritis, kidney disease, etc).

The risk of cardiovascular disease is further elevated in overweight and obese individuals due to changes in levels of adiponectin, a type of protein released by adipocytes1. Adiponectin helps regulate blood sugar levels (by increasing the insulin sensitivity of muscle, thus assisting in the uptake of blood sugar), and the uptake of fatty acids for use as an energy source. Normally, adiponectin levels remain consistent, signalling cells to take up and to either store or use sugar and fat for energy. But, in overweight and obese individuals, adiponectin levels decline so that improper signals are sent to fat cells. This results in reduced insulin sensitivity (increased risk of type 2 diabetes) and increased levels of fatty acids in circulation which can lead to plaque formation and higher risk of cardiovascular disease1.

Influence of obesity on mood and food choices
There is an increased prevalence of anxiety and depression amongst overweight and obese individuals. There are many reasons for this, including alteration in one’s mood due to a negative body image, socioeconomic status (Obesity and depression are more prevalent amongst people of lower socioeconomic status) and lack of physical activity. Unfortunately, when many people are depressed they often turn to “comfort food” (i.e. high fat, high sugar foods) to improve their mood. Why does this happen? This happens due to both short- term and long -term effects of high fat, high sugar foods on the brain and subsequently on mood. In the short term, these foods trigger a release of mood enhancing neurotransmitters in the brain, making a person feel good3-4. Feeling better while eating then reinforces one’s desire for comfort food, causing one to continue to eat high fat and high sugar foods.

Over the long term this eating pattern influences mood by changing the reward centres in the brain. When exposed to the consumption of high fat and high sugar foods over the long term, there is decreased function of certain neurotransmitters (specifically dopamine) in the brain4. Altered levels of these neurotransmitters impact mood (anxiety and depression), decrease one’s ability to respond to acute stress and increases one’s desire to use substances (high fat and high sugar foods) that will subsequently stimulate the release of the “pleasurable” neurotransmitters4. Interestingly, the changes in reward centres of overweight and obese individuals are similar to that seen in people with alcohol and drug addiction.

Given these changes within fat cells and in the brain, it is not surprising that losing weight and maintaining a healthy weight can be a struggle for many people. If you are trying to lose weight, it is important to address all as the elements that contribute to achieving and maintaining a healthy weight. These include eating a healthy diet, being physically active, managing stress and mood, promoting good sleep, and adressing possible medication side effects. These are factors that I address when trying to help a person to achieve a healthy weight.

Graham Beaton is a Doctor of Naturopathic Medicine in practice at Ottawa Collaborative Care Centres. If you are concerned about your weight, how weight might be influencing your health, or if you would like guidance on how to promote and maintain a healthy weight, please contact Graham at 613-290-6115.

1. Greenberg, A. and Obin, M., Obesity and the role of adipose tissue in inflammation and metabolism. Am J Clin Nutr. 2006; 83(suppl): 461S-465S.
2. Das, U.N., Is obesity an inflammatory condition?. Nutrition. 2001; 17: 953-966
3. Geiger, B.M. et al., Deficits of mesolimbic dopamine neurotransmission in rat dietary obesity. Neurosciences. 2009 April 10; 159(4):1193-1199
4. Sharma, S. and Fulton, S., Diet-induced obesity promotes depressive like behaviour that is associated with neural adaptations in brain reward circuitry. Int J Obes. 2013 March; 37(3): 382-389

Tags: , , , , ,