Far from being ‘just’ the male sex hormone, testosterone plays a crucial part in men and women to optimise muscles, bones and perhaps most surprisingly, our brain’s health – as well as managing the amount of fat we store.
Tim, a 40-year-old gentleman, attended the vitality clinic with autophony, which caused him to perceive his voice louder than usual. A possible cause was that his Eustachian tube valve remained open, allowing sounds to travel from the nose and throat to the ear, making him hear his voice loudly.
On attending the ENT (Ear, Nose and Throat) Clinic, it was suggested that his symptoms could be related to acid reflux. His diet was high in processed food, and he reported having stomach acid after eating fish and chips.
An upper GI endoscopy confirmed acid reflux and a pre-cancerous condition related to it, known as Barrett’s oesophagus, and he was prescribed omeprazole (acid pill).
He had low libido, a family history of autism, and suffered from anxiety, pursuing a very stressful job. Given the high pressure, he had to take an extended holiday in a health retreat for two months.
Tim tended to wake at 3 am, finding it hard to get back to sleep (a sign of poor blood sugar control). He often had restless legs and experienced cramps over his legs (magnesium deficiency).
Despite being highly educated, he noticed difficulty in following unstructured conversations. He enjoyed two big meals daily but had difficulty curbing his appetite and stopping eating (high leptin). He had wasted muscles and spoon-shaped ridged nails, suggesting iron and mineral deficiency.
His BMI was normal at 21.7, but he had a high waist/hip ratio of 0.97 (excess belly fat). Routine general tests were within the normal range, apart from high cholesterol at 7.6 (normal <5).
The combination of wasted muscles, low libido and mild cognitive impairment suggested low testosterone. This triggered a bone density scan that confirmed optimal body fat (athletic level at 9%). Low muscle mass and significantly low bone density, which was diagnostic of osteoporosis.
The blog explores how testosterone levels influence muscle and fat mass, the impact of insulin in raising cholesterol levels but blunting ketone body formation in the liver, with serious implications for the brain’s energy sources, and how bone, muscle and brain health are connected.
While it can burn ketone bodies, the brain prefers glucose, consuming almost half our daily sugar intake. Therefore, optimal blood sugar control is essential for good cognitive function. Impaired synthesis of ketone bodies makes glucose the sole energy source for the brain.
The body stores glucose as glycogen in the liver and muscles. However, the limited storage of 2,000 calories can be depleted quickly, making it an unsustainable energy source.
High insulin makes the brain dependent on glucose as the primary energy source. This happens when ketone bodies are not available as an alternative fuel when the sugar level goes too low.
With compromised ketone body formation and limited body sugar stores, we need glucose from non-sugar sources to stabilise blood glucose levels and power the brain.
Since fat poorly diffuses through the blood-brain barrier (BBB) and does not convert into glucose, there are no other energy options apart from protein. The body can make glucose from proteins through gluconeogenesis (making sugar from other sources) in the liver, kidneys, intestine, and muscles.
What limits the formation of ketone bodies?
Fat is released from storage in adipose tissue and transported to the liver to be converted into ketone bodies. These are then redistributed to the body’s organs, including the brain, to be used as an alternative fuel.
High insulin limit the production of ketone bodies, the brain’s alternative fuel by reducing the breakdown of fat from adipose tissue, which supplies free fatty acids, the substrate for ketone bodies.
Low insulin during fasting or starvation stimulates ketosis, which breaks down fat and synthesises ketone bodies. However, high insulin during feast times inhibits the generation of ketone bodies because they are not needed when there is plenty of glucose around.
High insulin also diverts a molecule known as HMG COA to make cholesterol instead of converting it to ketone bodies. The patient’s profile showed high cholesterol (7.6), which suggests a high insulin level. The enzyme that converts HMG COA to cholesterol is HMG COA reductase, which is well known to be blocked by statin (cholesterol pills).
Limited ketone body synthesis, leave the brain entirely dependent on glucose as an energy source. At times of low blood sugar, the patient must obtain glucose from non-carb sources.
This triggers gluconeogenesis, where the body breaks down muscle to make sugar—resulting in significant muscle loss, as revealed on the bone density (DEXA) scan, which also showed low bone density diagnostic of osteoporosis.
What part does testosterone play in all this?
Testosterone increases muscle protein synthesis, muscle mass and strength, resulting in bigger and stronger muscles. The testosterone level rises and stays up for several hours after exercise.
One study reported that you cannot build muscle while having low testosterone, irrespective of how hard your workout is.
Cardio exercise helps you burn fat, while strength training supports the development of lean muscle mass, which boosts your metabolism and increases testosterone levels.
Testosterone replacement can increase muscle mass, but can cause unpleasant side effects such as acne, mood swings and weight gain.
Testosterone decline
The slow decline in testosterone levels with age is known as andropause (male menopause). It manifests as a decline in muscle mass, depression, and low libido. The level starts to decline at 40 by 1% to 3% yearly, resulting in the middle-age crisis. Characterised by accumulated belly fat and muscle wasting—giving the low testosterone ‘look’ of a large belly but thin limbs.
Low testosterone can shift the male to female pattern of storing fat around the hips and thighs.
How does testosterone affect body fat?
Low testosterone increases the synthesis and deposition of fat in the adipose tissue. It also slows down the metabolic rate, resulting in weight gain. Often complicated by the development of metabolic syndrome, the gateway to chronic diseases.
One study revealed that each one-point increase in BMI is associated with a 2% decline in testosterone levels. Low testosterone can change your appearance by having less fat on your cheeks.
Another study demonstrated that participants given testosterone lost 3kg more body fat than those on a placebo and maintained their muscle mass. While those on a placebo lost 3.5kg muscle mass.
Fluctuations in blood sugar and high insulin cause your body to produce more oestrogen and sex hormone binding globulin (SHBG), resulting in low effective free testosterone.
Testosterone crosses the blood-brain barrier (BBB) and activates cortical networks to give a sense of psychological well-being. Testosterone deficiency impairs quality of life due to fatigue, reduced physical strength, low mood, irritability, anxiety, and brain fog.
In one study, men with low testosterone had poor cognition compared to men at the same age with high testosterone. Testosterone enhances sex drive and performance in men. In another study, it was found that taking a testosterone replacement increased muscle mass but did not improve brain function.
Magnesium and vitamin D naturally boost testosterone, as do natural herbs such as Maca, saw palmetto, Ashwagandha, and Tongkat Ali. Muscle-building exercises can restore your testosterone level so you look good, with flat belly, stronger muscles and bones, more energy, and thick hair.
Physiological levels of testosterone have the same impact on women’s muscles, bone and brain health as men’s. Testosterone increases libido in women and men.
In conclusion, Healthy carbs and strength training boost testosterone. This gives you ideal body weight and cholesterol and positively impacts your muscle, bone, and brain health. Please share your thoughts and questions by commenting on this piece and subscribe to the newsletter so you don’t miss further vital information. Thank you!
References
Why does brain metabolism not favour burning fatty acids to provide energy?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3790936/
Why does brain metabolism not favour burning fatty acids to provide energy?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3790936/
Low serum testosterone concentration is associated with poor cognitive performance in older men but not women
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8591394/
Effect of testosterone Supplementation on functional mobility, cognition and other parameters in older men
Gluconeogenesis
Does testosterone affect the female body in the same way, since females also produce testosterone (in much smaller amounts)?
The physiological levels of testosterone affect the female body similarly to males. It supports healthy muscle, bone, and brain. Pathological levels of testosterone cause body hair, acne, PCOS and rarely diabetes. Thanks, Beatrix, for the great question.