Background
This Ruling forms part of a wider piece of work on ads relating to low testosterone, identified for investigation following complaints and intelligence gathered by our Active Ad Monitoring system, which uses AI to proactively search for online ads that might break the rules. See also related ruling published on 26 August 2026.
Ad description
Two paid-for Facebook ads for Numan digital healthcare, seen in January 2026:
a. The first ad had the caption “Testosterone deficiency is a battle, you don’t have to fight it alone”. Text stated, "40% OF MEN WITH OBESITY HAVE LOW TESTOSTERONE You’re not broken. You’ve just been running on empty, and no one’s checked the tank”. It also featured a clickable button labelled "Blood tests from £74.50". Small text stated, “Fui MNT, Dupuis P, Grossmann M. Lowered testosterone in male obesity: mechanisms, morbidity and management. Asian J Androl. 2014;16(2):223-31”.
b. The second ad had the caption “Testosterone deficiency is a battle, you don’t have to fight it alone”. Text stated "95% OF MEN WITH LOW TESTOSTERONE ARE UNDIAGNOSED You’re not broken. You’ve just been running on empty, and no one’s checked the tank". It also featured a clickable button labelled "Blood tests from £74.50". Small text stated, “Liu VN, Huang DR, Alaa A, Hayhoe B, El-Osta A. Awareness and prevalence of the symptoms of testosterone deficiency: a cross-sectional survey of community-dwelling men in the UK. BMJ Open. 2025;15(7):e094145”.
Issue
The ASA challenged whether the claims in the ads about low testosterone could be substantiated.
Response
Vir Health Ltd t/a Numan said that ad (a) ran from 17 December 2025 to 7 January 2026 and ad (b) ran from 17 December 2025 to 21 April 2026. Neither had been in use since. Numan said the ads’ purpose was to raise general awareness of testosterone-related health considerations and to encourage individuals, particularly those in at-risk groups such as men with obesity, to consider testing and, where appropriate, seek clinical advice.
Numan said that the claim in ad (a) that “40% OF MEN WITH OBESITY HAVE LOW TESTOSTERONE” was based on, and accurately reflected, peer-reviewed, published evidence from an analysis of free testosterone concentrations of 1,849 men (nondiabetic and diabetic) from the Hypogonadism In Males study (HIMS), as reported in an expert-authored review; hypogonadism being testosterone deficiency. They said it was also supported by a systematic review and meta-analysis.
Numan said the 40% claim was presented as a population-level prevalence and that, although the cohort was US-based, the findings were valid for a UK audience for two reasons. First, both the US and UK classify obesity as a BMI greater than or equal to 30, in line with the World Health Organization classification. That was demonstrated by the NHS, National Institute for Health and Care Excellence (NICE) and clinical researchers, who used the same measure.
Second, Numan described the prevalence finding as consistent with, and conservative compared to, wider, peer-reviewed evidence, as set out in a systematic review and meta-analysis they provided, which included a section on male hypogonadism that reviewed 18 studies and covered a total of 4,546 men with obesity. It reported a prevalence of biochemical hypogonadism of 42.8% when measured by total testosterone.
Numan noted that the systematic review and meta-analysis discussed the two-way relationship between obesity and testosterone: low testosterone possibly being not only the consequence of obesity but also the cause. They stated, however, that the 40% claim in ad (a) was a population-level prevalence finding rather than a causal claim, and that it did not assert a diagnosis or clinical outcome for any individual.
Numan said that the claim in ad (b) that “95% OF MEN WITH LOW TESTOSTERONE ARE UNDIAGNOSED” was drawn from the report cited in the ad. It involved a survey of 974 UK men. The report stated that 49% of respondents had symptom profiles suggestive of testosterone deficiency and that 5% reported a formal medical diagnosis.
On review, Numan accepted that the claim “MEN WITH LOW TESTOSTERONE” in ad (b) was not substantiated by the report because the cohort surveyed were men with symptoms of low testosterone, rather than clinically confirmed to have low testosterone. Numan explained that, given that unintended misinterpretation of the data, they had withdrawn ad (b).
Numan further accepted that, while the underlying figures were taken from published, peer-reviewed studies, there had been an inadvertent and genuine error in the interpretation of the studies. They had reviewed their internal processes for substantiating claims so that statistics drawn from research would be represented accurately in future.
Assessment
Upheld
The ASA considered that the claim in ad (a) “40% OF MEN WITH OBESITY HAVE LOW TESTOSTERONE” implied 40% of all men of all ages with obesity had low testosterone. To support the claim Numan provided the review cited in the ad. It had been commissioned by a peer-reviewed journal and analysed a range of research into low testosterone and obesity. One of the studies quoted was an analysis of 1,849 community dwelling obese US American men using data from a cross-sectional study, which had been conducted on behalf of a pharmaceutical company. We noted that it involved a non-UK population, and that the findings of the cross-sectional study were published in 2006 and thus 20 years old. The analysis was published in 2010 and thus 16 years old.
The cross-sectional study had actually looked at 2,162 participants but the analysis only reported on 1,849 men. The others had been excluded for various reasons such as taking antiretroviral drugs, testosterone replacement therapy, steroids, narcotics or antibiotics, or because of missing data related to BMI or hormone concentrations. The review cited in ad (a) stated that, of the 1,849 obese men, 40% had low testosterone levels. However, that inaccurately represented the findings of the analysis of the cross-sectional study data. While the analysis did state that 40% of obese men aged 45 or over had subnormal free testosterone concentrations, that 40% figure was based on only 489 participants: obese men who were non-diabetic. Overall, 962 participants in the study were non-diabetic men who were lean or overweight, rather than obese, and 398 participants were diabetic, and of those 398, 227 were obese and the prevalence of subnormal free testosterone concentrations in the obese diabetic men was 50%. Therefore, while the analysis of the cross-sectional study did conclude 40% of the non-diabetic obese participants had subnormal free testosterone, the review cited in ad (a) wrongly stated that this was based on the total cohort of 1,849, rather than the true figure of 489, and did not make clear it was exclusively non-diabetic men. We also considered that the claim “40% OF MEN WITH OBESITY HAVE LOW TESTOSTERONE” did not make clear that the finding did not apply to men between the ages of 18 and 44. We therefore considered that neither the review nor the analysis substantiated Numan’s claim regarding the population prevalence of low testosterone in men with obesity.
Numan had further provided a systematic review and meta-analysis of other peer-reviewed evidence to support the 40% claim, which covered 18 studies published from 1994 to 2016, comprising a total of 4,546 obese male patients with a mean age from 27.9 to 61.9. We acknowledged the pooled prevalence of hypogonadism, defined by low total testosterone, across the studies covered by the systematic review and meta-analysis: 42.8%. However, we understood that this was when measured by total testosterone: all the testosterone in someone’s blood. Conversely, we understood Numan’s 40% claim to be based on free testosterone concentrations: testosterone not bound to proteins.
The systematic review and meta-analysis found the pooled prevalence of hypogonadism when free testosterone was measured to be 32.7%. We also remarked that, as well as the pooled prevalence across the studies of 42.8%, the systematic review and meta-analysis reported prevalence of hypogonadism as ranging from 0 to 51.5% across the studies. We considered that this suggested a more nuanced picture than the figure of 42.8% or the claim of 40% implied.
Further, all but one of the studies covered by the systematic review and meta-analysis were described as being of higher risk of bias because they had performed only a single measurement of testosterone. We considered that this further called into question the validity of the 42.8% figure as a means of judging the 40% claim. We therefore considered that the systematic review and meta-analysis was not adequate substantiation for the 40% claim in ad (a).
We next considered the claim in ad (b) that “95% OF MEN WITH LOW TESTOSTERONE ARE UNDIAGNOSED”. We acknowledged that Numan said that the claim was the result of an unintended misinterpretation of the data. Numan accepted that “men with low testosterone” was not substantiated by the cross-sectional survey referenced in the ad, because the cohort were men with symptoms of low testosterone rather than with clinically confirmed low testosterone. We welcomed Numan’s assurance that they had withdrawn ad (b) on the basis that it did not support that direct claim.
Because we had not seen adequate substantiation for the health-related claims made, we considered the ads were misleading and breached the Code.
The ads breached CAP Code (Edition 12) rules 3.1 (Misleadingness), 3.7 (Substantiation) and 12.1 (Medicines, medical devices, health related products and beauty products).
Action
The ads must not appear again in the form investigated. We told Vir Health Ltd t/a Numan not to make claims about the occurrence of low testosterone in the male population without adequate substantiation.
