This article is for health science popularization purposes only and is provided for informational reference. It does not constitute medical advice. Please consult a qualified physician for any health concerns.
You may have a normal weight and a Body Mass Index (BMI) within the standard range, yet stubborn belly fat that never seems to go away. This is not simply a matter of "middle-aged spread"—a condition known as "Thin Outside, Fat Inside" (TOFI) is quietly increasing your cardiovascular and metabolic risk. Research indicates that approximately 14% of adults with normal weight have central obesity, meaning excess visceral fat [1]. They may not look overweight, but their fat surrounds the liver, pancreas, and intestines, posing greater metabolic harm than subcutaneous fat. A review published in the Canadian Family Physician noted that individuals with normal weight but high waist circumference have a significantly higher risk of cardiovascular mortality compared to those with both normal weight and normal waist circumference [2].
Here are 5 signs to help you determine if you fall into the "TOFI" category.
Signal 1: Waist Circumference Exceeds Standards. For men, a waist circumference ≥90 cm, and for women, ≥85 cm (Chinese standard), warrants vigilance even if your BMI is normal. Waist circumference reflects visceral fat levels and offers better early warning value than the number on the scale.
Signal 2: Apple Body Shape. You have slender limbs but a protruding abdomen, with fat preferentially accumulating within the abdominal cavity. Compared to the pear-shaped body type where fat is stored around the hips and thighs, the apple shape indicates a higher proportion of visceral fat and greater cardiovascular risk.
Signal 3: Abnormal Lab Test Results. Triglycerides >1.7 mmol/L, fasting blood glucose >5.6 mmol/L, and low HDL cholesterol (men <1.0 mmol/L, women <1.3 mmol/L) are all early signs of metabolic syndrome and are closely associated with visceral fat [3].
Signal 4: Fatty Liver. An ultrasound indicating fatty liver or mildly elevated transaminase levels. Globally, about one-quarter of adults are affected by non-alcoholic fatty liver disease, including many individuals with normal weight. Inflammatory factors secreted by visceral fat directly damage the liver.
Signal 5: Elevated Blood Pressure. Visceral fat activates inflammatory and renin-angiotensin pathways, driving up blood pressure. If your blood pressure exceeds 130/85 mmHg and your waist circumference is also above the standard, this needs serious attention.
What to Do? A combination of aerobic exercise (150 minutes per week) and strength training (2-3 times per week) is an effective strategy for reducing visceral fat [4]. Dietarily, reduce refined carbohydrates and sugary drinks, while increasing dietary fiber and high-quality protein intake. Ensuring 7-8 hours of sleep is also crucial—insufficient sleep promotes elevated cortisol levels, which drives fat accumulation toward the abdomen.
Remember: Measuring your waist circumference provides a better reflection of your metabolic health than weighing yourself. Measure yours today.
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References Stefan N, Schick F, Häring HU. Causes, characteristics, and consequences of metabolically unhealthy normal weight in humans. Cell Metab. 2017;26(2):292-300. PMID: 28768170. Després JP. Normal-weight central obesity: Unique hazard of the toxic waist. Can Fam Physician. 2019;65(6):397-402. PMID: 31189627. Jayedi A, Soltani S, Zeraati H, et al. Anthropometric and adiposity indicators and risk of type 2 diabetes: systematic review and dose-response meta-analysis of cohort studies. BMJ. 2022;376:e067516. PMID: 35042741. Ismail I, Keating SE, Baker MK, Johnson NA. A systematic review and meta-analysis of the effect of aerobic vs. resistance exercise training on visceral fat. Obes Rev. 2012;13(1):68-91. PMID: 21951360. © 2026 Sun Shenghua (Beijing) Medical Technology Co., Ltd.