Updated 20 May 2014

How your weight influences your brain

Does being over- or under weight influence how your brain works? DietDoc takes a closer look.

In the second part of my series on factors which influence how efficiently our brains work, we consider the factors of being either under- or overweight.

Read Part 1: Can the right foods during pregnancy make your child smarter?

Over- and underweight

Both imbalances in body weight have an effect on brain function, but being underweight - either induced by starvation due to economic consequences, famines and other disasters, or self-induced by eating disorders such as anorexia nervosa, has been identified as a factor that can cause major damage.

Read: Anorexics and the obese are wired differently

Underweight and disordered eating

The deficiencies of total energy in the form of glucose to fuel the brain, of omega-3 fatty acids EPA ad DHA which are the building blocks of the brain and CNS, and of protein, plus all the vitamins and minerals which influence the smooth function of the nervous system and its control centre, the brain, all hamper normal function.

Read: Omega-3 fatty acids are great for helping kids learn

To address these serious deficiencies of the vital nutrients that contribute to nervous system functioning, it is essential that patients with any type of disordered eating (anorexia  nervosa, bulimia, orthorexia), should be assisted to start eating a balanced diet that provides adequate quantities of carbohydrates, protein, healthy fats, omega-3 fatty acids and a full complement of vitamins and minerals.

This is one of the reasons that patients with eating disorders should be under the care of a registered dietitian who is aware of the importance of not just restoring food intake, but of redressing the serious imbalances of the patient’s previous diet.

Overweight and the brain

Although there is some indication that the inflammatory processes associated with being overweight and obese may play a role in how the brain functions, we are not yet sure to what extent being overweight influences brain efficiency.

We are all aware that some overweight and obese patients tend to be depressed, but researchers are working on trying to unravel if the patients become depressed because of being overweight and eating an unbalanced diet, or if the depression is the trigger that causes the overweight.

Read: The link between diet, obesity and depression

We are aware of the ‘self-medication’ that many patients use to lift their mood by eating certain foods (chocolates, sweets and other sugary foods) thus increasing their serotonin levels (see below), but the interplay of cause-and-effect between brain function and overweight remains to be fully elucidated.

Now read: The foods neurotransmitters need to transmit signals between the brain and nervous system

Read more:

Metabolic syndrome (MetS) is associated with cognitive and brain impairments in adolescents
It's a fact: The obese brain craves high kilojoule foods
How your diet affects your brain function

Ask Dr Ingrid, aka DietDoc, questions about diet and nutrition

References: (Escott-Stump S (2014). No-Nonsense Nutrition for a Healthy Brain. Paper presented at: Nutritional Solutions CNE Event, Johannesburg, 11 April 2014; Zeisel SH, Da Costa K-A (2009). Choline: An essential nutrient for public health. Nutrition Reviews, Vol 67(11):615-623.)
Image: The obese brain, Shutterstock

Dr Ingrid van Heerden is a registered dietician and holds a doctoral degree in Nutrition and Biochemistry. She believes that "we are what we eat" and offers free nutrition and weight loss advice via her DietDoc service on Read more of her articles.


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