Tim Spector says genetics is the main driver of acne, not diet
"we did a twin study over about 15 years ago cuz my wife's a dermatologist and it showed quite convincingly that genetics were probably the major factor in acne. you know, the oiliness of your skin, um how those you know, all the follicles uh are working overtime with excess oils or not."
About this episode
ZOE host Jonathan Wolf interviews Professor Tim Spector and Professor Sarah Berry on how different forms of dietary sugar affect metabolism and health. Berry explains that the body needs glucose in the blood but does not require dietary sugar, because glucose can be produced from other macronutrients and starches are broken down into glucose. The guests focus on “free sugars” (added sugars, honey, syrups and fruit juice) versus “intrinsic” sugars within whole foods, arguing that structure and fibre slow absorption and reduce sharp glucose excursions.
Berry describes a rapid sugar-driven rise in blood glucose followed by an insulin “overshoot” that can lead to a later dip; she says ZOE research links that dip after breakfast to earlier eating and an average of about 320 extra calories consumed across the day, alongside lower energy and mood. Spector argues repeated high glucose spikes stimulate inflammation and says this has been associated with brain and mental health outcomes, while noting much evidence is observational.
On cancer, Berry says the stronger link is indirect, via excess calorie intake and obesity-related inflammation, and she adds that WHO does not classify sugar as a carcinogen. The episode also challenges common beliefs: Spector says genetics is likely the major factor in acne, and the guests advise caution with sugary drinks, fruit juice and some “healthy-looking” products such as low-fat flavoured yoghurts, breakfast cereals and sauces. A mid-episode segment promotes ZOE-branded snack bars.
Key takeaways
- Berry says the body needs glucose but does not need to consume sugar to maintain blood glucose.
- The guests distinguish free sugars (including juice and honey) from intrinsic sugars in whole fruit.
- Berry says ZOE data links a post-breakfast glucose dip to ~320 extra calories consumed that day on average.
- Spector argues repeated glucose spikes can drive inflammation that has been associated with mental and brain disorders in studies.
- Berry says the stronger evidence on sugar and cancer is indirect, via obesity and inflammation, and notes WHO does not class sugar as carcinogenic.
- Spector says a twin study found genetics to be the major contributor to acne, with diet a smaller factor.
- They recommend checking labels for added sugars and warn that UK labels typically report total sugar rather than free vs intrinsic.