Winter Testosterone
Do T levels fluctuate throughout the year? Are they really lower in the winter and higher in the summer? Here's what you need to know.
We've known for a while that male and female testosterone levels follow a diurnal or daily rhythm: they're highest in the morning (if you've slept well) and lowest in the late afternoon and evening. For men, our highest natural T levels are between 6:00 AM and 10:00 AM. Some suggest training during this time to take advantage of peak T.
But what about yearly? Are there peak months for testosterone production? Let's see what science says.
Lots of Studies, Somewhat Mixed Results
According to most studies, male testosterone levels are highest in the summer and lowest in the winter.
For example, one study analyzed the clinical data from 7,491 men of all ages. The results showed a seasonal distribution with higher T levels in summer and a direct correlation to environmental temperatures and daylight duration. Specifically, testosterone was at its highest in August and at its lowest in March.
Most studies show a similar pattern, but not all. For example, another study looked at men in Pittsburgh (where there are distinct seasons) and Miami (where there aren't distinct seasons). Those researchers found no significant variability in T levels between seasons. However, they did find "differing total testosterone levels between men who reside in two different climates." Miami men had slightly higher T levels year-round than Pittsburg men.
If we do an informal meta-study on the topic, most researchers agree that men experience seasonal testosterone fluctuations, with the lowest levels reported in the winter.
What Causes This?
Most researchers say the T fluctuations are caused by day duration and sunlight. This is true for men and women, but it's less pronounced in females.
Sunlight, of course, is a source of vitamin D, and vitamin D directly influences testosterone synthesis in both men and women, via some differing mechanisms. Aside from testosterone synthesis, Vitamin D modulates SHBG levels, affecting the amount of free (biologically active) testosterone available in your body.
What to Do About It
Put all this together and it makes sense to supplement with vitamin D (or more of it) in the winter. The most absorbable and usable form is microencapsulated D3, sold as D Fix High Absorption Vitamin D (Buy at Amazon). Take 5000 IU per day – one softgel of D Fix. If you suspect your levels are very low, try 10,000 to 20,000 for several days, then drop back down to 5000 IU.
If you need to pull out the big guns, take a testosterone-boosting supplement like Longjack (Eurycoma or Tongkat Ali). Use the proven LJ100 form in a pharmaceutical delivery system to increase bioavailability, as found in Omega-Man High Absorption Longjack (Buy at Amazon).
Signs of Low Winter T
A blood test is best, but here are some signs to watch out for. In this context, note any differences from summer to deep winter:
- Increased body fat (particularly in the abdominal region) and decreased muscle mass, even if diet and training are about the same throughout the year.
- Decreased energy levels, even after adequate rest.
- Reduced sex drive or bedroom performance; fewer or less rigid morning erections.
- Mood changes including increased irritability, depression, or lack of drive.