What happened in this episode?
ZOE’s host speaks with Professor Jimmy Bell, a molecular imaging and metabolism researcher, about how fat distribution — particularly visceral fat around abdominal organs — relates to cardiometabolic risk. Bell argues that adipose tissue should be treated as an active organ, not inert energy storage, describing how inflammatory signalling associated with visceral fat may affect mood and behaviour, while also acknowledging uncertainties in mechanisms.
Bell explains that traditional measures such as BMI can miss “thin outside, fatty inside” (TOFI) body composition, and attributes some cases to maintaining weight through dieting without exercise, which he says can worsen the fat-to-muscle ratio. He ranks visceral fat as the highest-risk depot, followed by liver, pancreas and intramuscular fat, and discusses sex and menopause-related shifts in fat distribution.
On diet, he argues that fat composition in the body reflects dietary fat quality, saying unsaturated fats are preferable and that fat “turnover” may take two to three years, citing Swedish work. He also discusses alcohol as an inflammation-related risk, particularly for people already metabolically unhealthy.
On interventions, Bell says internal fat depots (visceral, liver and pancreas fat) are metabolically responsive and can change significantly within 12 weeks under calorie reduction plus improved diet quality. He stresses resistance training and sufficiently intense activity (becoming breathless) to improve body composition, and warns that yo-yo dieting can progressively worsen the fat-to-muscle ratio.
Bell calls GLP-1 agonists effective for weight loss but says there is still unclear published evidence on muscle loss and muscle quality during treatment, raising concern about future sarcopenia risk if exercise is not included.
