Have you ever heard the term “skinny fat”? It describes people who sit within a healthy weight range but still carry excess body fat. Even though they don’t appear overweight, their body fat percentage puts them at a higher risk of metabolic issues.
It’s well known that high‑protein diets can support weight loss. But can increasing protein also help reduce excess body fat in women who appear to be within a healthy weight range? That’s exactly what this study explored.
Understanding Normal Weight Obesity
Normal Weight Obesity (NWO) is when someone has a normal BMI but a body fat percentage above 30% for women or 20% for men. Even without excess weight, this still increases the risk of metabolic disease.
Research shows that women with NWO often have a lower resting metabolic rate due to reduced lean body mass. That makes preserving muscle a major priority for improving health and reducing body fat.
High‑protein diets help protect lean mass and support fat loss in overweight individuals, but very little research has focused specifically on women with NWO.
How the Study Was Conducted
Researchers ran a 12‑week double‑blind randomised controlled trial to examine the effects of a high‑protein diet on body composition and appetite in women with NWO.
Participants were aged 30–60, had a BMI between 18.5–25 and a body fat percentage above 30%. Women who were smokers, pregnant, breastfeeding, using birth control within 6 months, living with chronic disease, using drugs or following a high‑protein diet were excluded.
Fifty women participated and were randomly assigned to one of two groups:
- High‑protein (HP): 25% of total energy from protein
- Standard‑protein (SP): 15% of total energy from protein
Both groups consumed eucaloric diets (equal calories). Researchers measured body weight, fat mass, lean mass, appetite and waist circumference at the start and after 12 weeks.
Key Study Results
Of the original group, results were collected from 24 women in the HP group and 23 in the SP group due to dropouts and non‑compliance.
Lean Body Mass
- The HP group increased lean body mass.
- The SP group saw no significant changes.
Fat Mass & Body Fat Percentage
- The HP group had lower fat mass and a lower body fat percentage.
- Waist circumference decreased more in the HP group.
Appetite & Body Weight
- No significant changes in appetite were seen in either group.
- Body weight remained stable across both groups.
What the Study Tells Us
A 12‑week high‑protein diet significantly improved body composition in women with NWO, increasing lean mass and reducing fat mass — without weight loss. This highlights how powerful protein can be when someone’s goal is to change their body composition rather than their scale weight.
However, the study had limitations, including the method of assessing appetite and the inability to track protein compliance through urine samples. The findings also only apply to women aged 30–60 without other health conditions, so more research is needed for broader recommendations.
