Hormones

1. Hormoneswell supported · human dataAdded 8 October 2026

   Testosterone therapy improves heart risk markers but raises an arrhythmia flag

   Across 31 trials in 9,437 middle-aged and older men, testosterone replacement therapy lowered total cholesterol, triglycerides and LDL cholesterol and improved measures of artery health, but arrhythmias were more common in men on treatment.

   ⚠What it shows: Solid on the risk markers, unresolved on heart rhythm: results pooled from 31 trials in 9,437 middle-aged and older men with low or low-normal testosterone, lasting from 40 days to 36 months. The extra arrhythmias showed up clearly in the data, but their real-world clinical importance remains uncertain.Meta-analysis · Endocrine

   Full breakdown →ApoB explained →Heart Age Calculator →Cardiovascular safety in middle-aged and older men under testosterone replacement therapy: a systematic review and meta-analysis. Endocrine 2026
2. Hormoneswell supported · human dataAdded 27 September 2026

   GLP-1 drugs showed no clear rise in thyroid cancer across 45 trials

   Across 45 randomised trials, GLP-1 receptor agonists were associated with a modest rise in thyroid disorders overall, but no significant increase in any single condition, including thyroid cancer, hyperthyroidism, hypothyroidism, thyroiditis, thyroid mass or goitre.

   ⚠What it shows: Reassuring on the specifics but not fully settled: results pooled from 45 trials found no significant rise in thyroid cancer or any single thyroid condition. These diseases are rare, so even trials this size can miss small risks, and the modest rise in thyroid problems as a combined category keeps the question open.Meta-analysis · Front Endocrinol (Lausanne)

   Full breakdown →GLP-1 explained →Use of GLP-1 Receptor Agonists and Occurrence of Thyroid Disorders: a Meta-Analysis of Randomized Controlled Trials. Front Endocrinol (Lausanne) 2022
3. Hormonespreliminary · human dataAdded 19 September 2026

   Lifting spikes testosterone, but push too long and it dips for days

   A review of 15 randomised trials in 251 people maps how acute exercise moves testosterone: lifting raises it more and for longer than cardio, after which levels typically recover within 1 h, while extended high-intensity exercise can suppress testosterone during recovery for up to 72 h as cortisol works against it.

   ⚠What it shows: Useful as a map rather than a verdict: the 15 trials covered just 251 people between them and were reviewed precisely because earlier results disagreed. Every change described is short-lived, so nothing here shows exercise raising resting testosterone for good.Systematic review · PeerJ

   Full breakdown →Cortisol explained →Recovery Readiness Index →Effect of acute exercise on the dynamics of testosterone levels: a systematic review of randomized controlled trials. PeerJ 2026
4. Hormoneswell supported · human dataAdded 23 August 2026

   Fasting lowered the hunger hormone instead of raising it

   A meta-analysis of 16 trials found fasting regimens significantly lowered both leptin and ghrelin, the hormone that drives hunger, in healthy, overweight and obese adults. Adiponectin rose only marginally and resistin did not change.

   ⚠What it shows: Encouraging rather than settled: results pooled from 16 trials in healthy, overweight and obese adults. Nobody has yet tested whether the hormone shifts last, and the rise in adiponectin fell short of clear significance.Meta-analysis · J Health Popul Nutr

   Full breakdown →Leptin explained →Calorie Deficit Calculator →The effectiveness of fasting regimens on serum levels of some major weight regulating hormones: a GRADE-assessed systematic review and meta-analysis in randomized controlled trial. J Health Popul Nutr 2025
5. Hormoneswell supported · human dataAdded 23 August 2026

   Ramadan fasting turns the hunger hormone up, not down

   Pooled data from 16 studies of 664 healthy adults show Ramadan intermittent fasting significantly raised ghrelin, the hormone that drives hunger, while leptin, insulin and gastrin showed no significant change.

   ⚠What it shows: Reasonably solid on the headline but thin underneath: results pooled from 16 studies of 664 healthy adults, yet only three of those studies measured ghrelin. The leptin studies disagreed with each other, so that null is less settled than it looks.Meta-analysis · Clin Nutr

   Full breakdown →Ghrelin explained →Effects of Ramadan intermittent fasting on hormones regulating appetite in healthy individuals: A systematic review and meta-analysis. Clin Nutr 2025
6. Hormoneswell supported · human dataAdded 22 August 2026

   A day or more without food dials down your active thyroid hormone

   Pooled data from 15 studies shows fasts of 24 hours or longer are associated with marked drops in the active thyroid hormones FT3 and total T3 and a moderate fall in TSH, while FT4 holds steady. That pattern points to reduced conversion of T4 into T3 rather than a shutdown of thyroid hormone production.

   ⚠What it shows: Solid on direction, fuzzy on size: results pooled from 15 studies of adults fasting at least 24 hours agreed that T3 falls while T4 holds, but the studies disagreed considerably on how big the FT3 drop was. None of this covers shorter intermittent fasting windows.Meta-analysis · Front Endocrinol (Lausanne)

   Full breakdown →Metabolic adaptation explained →BMR Calculator →Effects of fasting on thyroid hormone profiles: a systematic review and meta-analysis of TSH, FT3, FT4, and total T3 responses. Front Endocrinol (Lausanne) 2026
7. Hormoneswell supported · human dataAdded 16 August 2026

   Underactive thyroid predicts dying from heart disease, not getting it

   Across nine studies of 9,662 adults, people with hypothyroidism had 2.73 times the odds of cardiovascular death compared with those with normal thyroid function, yet showed no increased odds of developing cardiovascular events in the first place.

   ⚠What it shows: Take the mortality link seriously but not as proof of cause: results pooled from nine studies that followed 9,662 adults rather than testing any treatment. The absence of a link with developing heart disease was not significant, which the authors stress is not the same as showing no effect.Meta-analysis · Endocrine

   Full breakdown →All-cause mortality explained →Heart Age Calculator →Differential association of hypothyroidism with cardiovascular events and cardiovascular mortality: a systematic review and meta-analysis. Endocrine 2026
8. Hormoneswell supported · human dataAdded 10 August 2026

   Thyroid trouble may not be the anxiety driver it's made out to be

   Across 12 population-based studies of 676,658 people, links between thyroid problems and anxiety were small and mostly not statistically significant. Only an overactive thyroid showed a modest significant association.

   ⚠What it shows: Take the uncertainty seriously: this pools 12 population studies of 676,658 people, the most representative evidence yet, but the studies disagreed with each other, so anything from a modest link to no link at all remains possible.Meta-analysis · PeerJ

   Full breakdown →Thyroid disorders, thyroid autoimmunity, and anxiety-a systematic review and meta-analysis of population-based studies. PeerJ 2026
9. Hormonespreliminary · human dataAdded 10 August 2026

   Testosterone therapy cleared of raising heart attack and stroke risk

   In a trial of 5246 men aged 45 to 80 with low testosterone and high cardiovascular risk, testosterone gel did not increase major cardiac events compared with placebo, with events in 7.0% versus 7.3%. Atrial fibrillation, acute kidney injury and pulmonary embolism were more common with testosterone.

   ⚠What it shows: About as solid as single-trial safety evidence gets: 5246 men with low testosterone and existing heart risk were assigned at random to testosterone gel or placebo and followed for nearly three years on average. It shows no extra heart attacks or strokes, not that testosterone helps, and clots, heart rhythm problems and kidney injury were more common on treatment.RCT · N Engl J Med

   Full breakdown →Testosterone explained →Heart Age Calculator →Cardiovascular Safety of Testosterone-Replacement Therapy. N Engl J Med 2023
10. Hormonespreliminary · human dataAdded 8 August 2026

    The post-workout testosterone spike depends on how you measure it

    A meta-analysis of 21 studies found salivary testosterone and cortisol generally rise after acute aerobic, resistance and power exercise in men, but the size of the response varied heavily with study design and when baseline samples were taken, and the authors judged the overall evidence weak.

    ⚠What it shows: Only 2 of the 21 included studies were randomised controlled trials and 18 were uncontrolled; effect sizes differed sharply by design and baseline sampling time, and the authors call for standardised salivary hormone methodology.Meta-analysis · Sports Med

    Full breakdown →Cortisol explained →Recovery Readiness Index →Exercise-induced responses in salivary testosterone, cortisol, and their ratios in men: a meta-analysis. Sports Med 2015
11. Hormoneswell supported · human dataAdded 8 August 2026

    Low SHBG emerges as a telltale marker of PCOS

    Women with PCOS have significantly lower levels of sex hormone-binding globulin (SHBG) than women without the condition, according to a meta-analysis drawing on 62 studies. Therapeutic interventions improved SHBG levels in women with PCOS, which was linked to fewer PCOS-associated complications.

    ⚠What it shows: Meta-analysis of observational comparisons with very high heterogeneity between studies (I2 93.9%); shows an association, not causation, and SHBG is proposed as a candidate biomarker rather than a stand-alone diagnostic test.Meta-analysis · Syst Biol Reprod Med

    Full breakdown →Insulin Resistance →Sex hormone binding globulin - an important biomarker for predicting PCOS risk: A systematic review and meta-analysis. Syst Biol Reprod Med 2018
12. Hormonespreliminary · human dataAdded 6 August 2026

    Fasting left reproductive hormones largely alone

    Pooling 15 randomised trials in 954 adults, fasting and 20%-30% calorie restriction had largely neutral effects on reproductive hormones, with no significant change in testosterone (fasting WMD −0.88 ng/mL, p = 0.24; calorie restriction −0.02 ng/mL, p = 0.65) and no significant effects on SHBG, DHEA-S, FSH, LH, oestradiol, AMH, prolactin or progesterone. The one exception was free testosterone, which fell by 4.9 pg/mL, a result driven by some of the smaller trials.

    ⚠What it shows: Systematic review and meta-analysis of 15 randomised trials in 954 adults with GRADE assessment, but there was significant heterogeneity for testosterone, the free-testosterone signal rested on smaller trials, and the authors did not assess symptoms, so a neutral hormone panel is not the same as clinical neutrality.Review · Food Sci Nutr

    Full breakdown →Energy balance explained →Calorie Deficit Calculator →The Effects of Fasting and Caloric Restriction on Reproductive Hormones: A Systematic Review, Meta-Analysis, and GRADE Assessment. Food Sci Nutr 2026
13. Hormonespreliminary · human dataAdded 26 July 2026

    Andropause education improved sleep in retired men

    A four-week virtual education programme about andropause, delivered over WhatsApp, significantly improved general health and sleep quality scores in retired men compared with a control group, with effects assessed again two months later.

    ⚠What it shows: Quasi-experimental study of just 60 retired men in Iran (30 per group), relying on self-reported questionnaires; not registered as a trial and needs replication in larger, more diverse samples.RCT · Sleep Breath

    Full breakdown →Sleep Calculator →Effects of andropause-related health education on general health and sleep quality among retired men: a quasi-experimental study. Sleep Breath 2026

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