One of the most useful conceptual upgrades in midlife metabolic health is understanding that "body fat" isn't one thing. It's at least two — and the two have very different metabolic consequences.
Most weight-loss conversations conflate them. Most metabolic-health interventions target only one. Knowing the difference changes what you optimise for.
Subcutaneous vs. visceral
The two main types of body fat are:
- Subcutaneous fat sits directly under the skin. It's the fat you can pinch on your thigh, your upper arm, or just below the surface of your abdomen. It's relatively metabolically inert — it stores energy, helps insulate you, and isn't actively producing problematic signalling molecules.
- Visceral fat sits deep in the abdominal cavity, surrounding organs. You can't pinch it. It produces inflammatory cytokines, contributes directly to insulin resistance, aromatises testosterone to oestrogen in men, and is mechanistically linked to nearly every degenerative disease of midlife — cardiovascular, metabolic, hormonal.
For metabolic health, subcutaneous fat is largely cosmetic. Visceral fat is the problem.
How to know roughly where you stand
The most accurate measurement is a DEXA scan or MRI, which directly visualises visceral fat. These cost $100-200 in most U.S. states and give a precise picture.
The proxy measurements that work reasonably well:
- Waist circumference. Above 94cm for men or 80cm for women suggests elevated visceral fat. Above 102cm/88cm is high.
- Waist-to-height ratio. Waist circumference divided by height in cm. Above 0.5 is the rough threshold of concern.
- Apple-shape vs pear-shape distribution. Apple-shape (carrying weight in the abdomen) correlates with higher visceral fat than pear-shape (carrying weight in hips and thighs).
You can have a normal BMI and high visceral fat — the so-called "skinny fat" pattern. You can also have an above-normal BMI and low visceral fat (athletic build, more muscle and subcutaneous fat). The numbers on the scale don't tell you which you are.
What actually reduces visceral fat
This is where it gets interesting. Visceral fat responds to interventions in a slightly different priority order than total body fat does:
1. Strength training
Resistance training preferentially mobilises visceral fat over subcutaneous fat in trial after trial. The mechanism is partly hormonal (improved testosterone, growth hormone, and adrenaline response) and partly metabolic (increased muscle mass increases glucose disposal capacity, which reduces the need to store excess as visceral fat).
For middle-aged adults trying to reduce visceral fat specifically, strength training outperforms cardio at equivalent caloric expenditure.
2. Caloric deficit, but moderate
Weight loss in general reduces visceral fat. But aggressive caloric restriction (1,200 kcal/day for an average adult) tends to lose disproportionate amounts of muscle alongside the fat, which is metabolically counterproductive. Moderate deficits (300-500 kcal below maintenance) sustained over 6-12 months produce better visceral-specific outcomes.
3. Sleep
Chronic sleep deprivation independently increases visceral fat accumulation, even in the absence of any change in caloric intake. The mechanism is hormonal — elevated cortisol, disrupted leptin/ghrelin balance, impaired insulin sensitivity. Sleep is one of the most underrated visceral-fat-reduction interventions.
4. Reducing alcohol
Alcohol-derived calories preferentially deposit as visceral fat, particularly in men. The "beer belly" pattern is real and biological. Reducing alcohol from 15+ drinks per week to 5 or fewer often produces visible visceral fat reduction within 8-12 weeks.
5. The dietary layer
Insulin resistance and visceral fat reinforce each other. Dietary patterns that improve insulin sensitivity — adequate protein, whole-food carbs, sufficient fibre — also tend to mobilise visceral fat over time. The specifics matter less than the general pattern.
6. Targeted supplementation
Berberine and other AMPK activators have modest evidence for visceral fat mobilisation specifically, partly through improved insulin sensitivity, partly through direct metabolic effects. This is a small lever on top of the bigger lifestyle ones, but it's real.
Grenov isn't a weight-loss product, and we don't market it that way. What it is, is a metabolic-health support — and improved metabolic health includes a modest tilt toward less visceral fat retention over time. Most of the effect on body composition is downstream of improved insulin sensitivity rather than direct fat loss. The big lever for body composition remains lifestyle; Grenov adds modest support.
The honest summary
Visceral fat is the metabolically-relevant kind, and it's the kind that responds best to a stack of strength training, decent sleep, sane caloric balance, less alcohol, and consistent dietary patterns. It's also the kind that produces the most felt improvement when it goes — energy, mood, hormonal profile, daily comfort.
For adults over 40 thinking about body composition, the visceral target is the one worth optimising for. The scale tells you less.