Is Keto Tanking Your Testosterone?

The keto diet is considered very beneficial for those with metabolic issues, helping people drop weight, sharpen focus, and stabilize blood sugar. But there’s one big question that isn’t getting enough attention:

Is keto lowering your testosterone?

Testosterone isn’t just about building muscle or sex drive (though it plays a role there too). It's also critical for energy, mood, bone density, motivation, muscle maintenance, and metabolic health for both women and men. Under certain conditions, keto can quietly start to sabotage it.

Let’s break down why.

Why Does Testosterone Matter?

We all have testosterone, just in different amounts. In men, testosterone is produced primarily in the testes, with smaller amount produced in the adrenal glands. In women, it’s produced in the ovaries and adrenal glands.

Testosterone supports:

• Lean muscle mass and fat metabolism

• Libido and sexual function

• Bone strength

• Mental clarity and confidence

Low levels can lead to:

• Fatigue

• Mood issues

• Poor workout recovery

• Low motivation or drive

• Hormonal imbalance (especially in perimenopause and menopause)

How Keto Can Lower Testosterone

The ketogenic diet is typically very low in carbs, high in fat, and moderate in protein. While this works well for some people, it can throw off hormonal balance if not done carefully, especially long-term.

Here’s how:

1. Low Carbs = Low Insulin

Carbs trigger insulin, and insulin plays a role in supporting the release of GnRH (Gonadotropin-Releasing Hormone), a hormone that kicks off the cascade that leads to testosterone production. When carbs (and insulin) are chronically low, LH and FSH, key messengers from the pituitary gland may drop as well.

That means your body gets less signal to make testosterone in men and women.

2. Keto Can Raise Cortisol (Your Stress Hormone)

Low-carb diets are perceived as a stressor by the body, especially if you’re training hard, under-eating, or already juggling a lot in life. Chronic stress = elevated cortisol, which can suppress testosterone and other sex hormones over time.

High cortisol can also interfere with sleep quality, and poor sleep further tanks testosterone.

3. Your Thyroid Slows Down on Keto

Keto can lead to lower levels of T3, your active thyroid hormone. And since thyroid and sex hormones are closely linked, a sluggish thyroid can mean sluggish testosterone, too.

This is especially relevant for women, who are more prone to thyroid sensitivity and autoimmune thyroid conditions.

4. Keto Often Puts You in a Caloric Deficit

Many people eat fewer calories on keto, partly because fat is more satiating, and partly because cutting carbs limits food choices. But chronic under-eating sends the signal: "This is not a good time for reproduction." So the body turns down production of “non-essential” hormones, including testosterone, estrogen, and progesterone in favor of survival.

This is especially risky for active women or those in perimenopause, when hormone levels are already fluctuating.

Who’s Most at Risk?

You may be more vulnerable to keto-related hormone imbalances if you:

• Stay on strict keto long-term without breaks or carb refeeds (carb cycle)

• Combine keto with intense training or fasting

• Are chronically under-eating or skipping meals

• Already have low thyroid function

• Are going through perimenopause or menopause

• Have a history of irregular cycles or low libido

What to Do About It

You don’t have to ditch keto entirely, but it might need adjusting, especially if you're seeing signs of hormonal disruption.

1. Consider Targeted or Cyclical Keto

• Targeted keto: Add small amounts of carbs (20–50g) before workouts.

• Cyclical keto: Introduce higher-carb days 1–2 times per week to support hormone signaling, especially during the luteal phase of your menstrual cycle.

2. Track More Than Just Macros

• Monitor energy levels, libido, mood, cycle changes, and recovery

• Women: look for disrupted cycles or PMS changes

• Men: track strength, motivation, and morning energy levels

3. Don’t Fear Carbs

Some amount of carbs may be necessary for hormonal balance, especially complex carbs like root vegetables, fruit, and whole grains.

4. Get Tested

Use functional lab testing or consult with your provider to check:

• Total & free testosterone

• Sex hormone binding globulin

• Albumin

• DHEA-S

• Cortisol (saliva or DUTCH)

• Thyroid panel (TSH, free T3, free T4, reverse T3, thyroid antibodies)

• LH, FSH, estradiol, especially for women in perimenopause

Keto can be a powerful tool, but like any extreme diet, it comes with trade-offs. If you’re feeling amazing on keto, that’s great. But if your energy is crashing, your libido is gone, or your mood and recovery are tanking, don’t ignore it.

Testosterone isn’t optional.
It’s vital for strength, drive, resilience, and longevity in both women and men.