GLP-1s + Ashwagandha, Tongkat Ali, Tribulus: The Hormone Stack Evidence Review

A 42-year-old man starts semaglutide, watches his weight drop, reads some content about "natural testosterone optimization," and buys a $180/month stack of ashwagandha, tongkat ali, and tribulus. Six months later he's lost 30 lbs, his testosterone is up 200 ng/dL, his libido is stronger, and he credits the supplement stack.

The weight loss and testosterone recovery are real. The supplement-driven attribution is mostly wrong. Here's the actual evidence on these three commonly-stacked compounds, which one is worth running alongside a GLP-1, and which ones are mostly wasted money.

The testosterone recovery you're actually seeing

Before getting into the supplements, it's worth naming the dominant variable: GLP-1-driven weight loss itself produces substantial testosterone normalization in men with obesity. The ENDO 2025 data showed the proportion of men with normal total and free testosterone rose from 53% to 77% over 18 months of GLP-1 therapy, with no hormonal supplementation of any kind.¹

Any testosterone gains you experience during your GLP-1 journey are most likely driven by weight loss, improved sleep, reduced visceral-fat-driven aromatase activity, and restored insulin sensitivity. The herbal stack is riding on those effects, not causing them.

That said, one of the three has some legitimate data. Let's go through them individually.

Ashwagandha: the one with actual data

Ashwagandha (Withania somnifera) is an adaptogenic herb from Ayurvedic medicine. Unlike most adaptogens, it has multiple well-designed human RCTs supporting effects on:

• Cortisol reduction — 15–30% decrease in chronic stress markers.
• Testosterone increase — modest but measurable (10–20% increases in total testosterone in several RCTs of stressed or athletic men).
• Subjective anxiety reduction — consistent finding across studies.
• Sleep quality improvement — smaller effect but present in multiple studies.
• Exercise performance — small strength and VO2 max improvements in training studies.

The evidence is strongest for the cortisol-reducing and anxiety-reducing effects. The testosterone effects are consistent but modest — roughly the same magnitude as a good sleep protocol. Not life-changing on its own; worthwhile as part of a stack if cortisol is elevated.

For men on GLP-1s, ashwagandha may be particularly useful because:

• GLP-1 weight loss reduces visceral fat and its cortisol-driving inflammatory effects.
• Ashwagandha further reduces cortisol via different mechanisms.
• The combined effect may produce a larger testosterone recovery than either alone.

Protocol for ashwagandha

• Dose: 300–600 mg daily of a standardized extract (KSM-66 or Sensoril are the most studied).
• Timing: Split dose, morning and evening. Or single dose at night if sleep is the priority.
• Duration: Effects typically appear at 4–8 weeks. Not an acute supplement.
• Cycle: 3 months on, 1 month off is a common protocol, though continuous use has been studied safely for 12+ weeks.

KSM-66 Ashwagandha → Budget Ashwagandha →

Tongkat Ali: moderate evidence, growing interest

Tongkat Ali (Eurycoma longifolia) has been used traditionally in Malaysian and Indonesian medicine for male vitality. The human data is smaller than ashwagandha's but growing:

• Modest testosterone effects — several RCTs show small increases in total and free testosterone in men with low baseline levels.
• Cortisol reduction — reduces cortisol/testosterone ratio in stressed men.
• Mood and vitality — subjective improvements in energy and well-being.
• Exercise recovery — some evidence of reduced DOMS and improved recovery markers.

The effect size is smaller than ashwagandha's in most head-to-head comparisons, and the quality of available research is lower. Not bad, not transformative.

Protocol for Tongkat Ali

• Dose: 200–400 mg daily of a standardized extract (typically standardized to 1–2% eurycomanone).
• Timing: Morning, with or without food.
• Duration: Effects at 4–12 weeks. Slower onset than ashwagandha.
• Cycle: Most protocols use it continuously, though some evidence suggests 2-on/1-off cycling.

Tribulus Terrestris: the one without evidence

Tribulus is the single most-marketed "testosterone booster" in supplement retail and has the worst evidence to support the claims. Multiple well-designed RCTs in men with normal or low baseline testosterone have consistently shown:

• No significant effect on total testosterone.
• No significant effect on free testosterone.
• No significant effect on LH.
• Small, unreliable effects on libido in some studies — possibly placebo.

The mechanism claimed (LH elevation via the hypothalamic-pituitary axis) has not held up in controlled human trials. The marketing persists because:

• It's cheap to produce.
• Early animal studies showed effects that didn't translate to humans.
• It's often stacked with other compounds in "testosterone boosters" that may produce real effects, allowing the marketing to attribute successes to tribulus.

If you're buying a product that lists tribulus as the primary active ingredient, you're paying for placebo. Don't include it in your stack.

What about fadogia agrestis?

Fadogia agrestis is the newer entrant in the male hormone supplement space, popularized by podcast culture. The evidence base is:

• One small, methodologically limited rat study showing testicular testosterone production effects.
• Zero well-designed human RCTs.
• Anecdotal human reports that are not a substitute for data.
• Some concerning toxicology signals in the limited preclinical data.

Skip it. The evidence isn't there, and the safety profile is unestablished. If you want a podcast-popularized supplement with actual data, that's ashwagandha — not fadogia.

The evidence-based men's hormone supplement stack

Total monthly cost: roughly $50–$80. Significantly less than most "premium" testosterone booster stacks, with more evidence supporting each component.

Vitamin D3 + K2 → Zinc Picolinate → Magnesium Glycinate → Omega-3 →

Common mistakes on the hormone supplement stack

What the supplement stack won't do

Let's be honest about the ceiling. A well-designed supplement stack for a man on a GLP-1 might contribute:

• 20–50 ng/dL additional testosterone gain over what the GLP-1 + weight loss provides.
• Some reduction in subjective stress and anxiety.
• Slight improvement in sleep quality.
• Modest improvement in exercise recovery.

That's a reasonable improvement. It's not going to turn a 350 ng/dL testosterone into a 750 ng/dL testosterone on its own. The big variables remain weight, sleep, training, protein intake, and the GLP-1 itself.

For men with genuinely low baseline testosterone (under 300 ng/dL) after 12 months of GLP-1 therapy, supplements are not the answer. TRT evaluation is. For men with mid-range testosterone who want to optimize, an evidence-based stack can move the needle a bit.

The bottom line

Of the three herbal testosterone boosters commonly sold in stacks to men: ashwagandha has real data, tongkat ali has moderate data, tribulus has essentially no data. If you're going to supplement, ashwagandha is the worthwhile one.

But the bigger point: no herbal stack is going to drive testosterone recovery the way your GLP-1, your weight loss, your sleep, your training, and your protein intake will. The supplements are a supporting player, not the main event.

Vitamin D, zinc, magnesium, omega-3, ashwagandha, creatine. That's the evidence-based stack for about $60/month. Everything else is marketing.