Can You Be “Fat But Fit”? What Does the Latest Science Say?
- Alastair Hunt
- Apr 23
- 5 min read
Updated: May 3
The phrase “fat but fit” has long sparked debate in public health circles. Can someone be in a larger body and still be healthy if they exercise regularly? A new study published in the British Journal of Sports Medicine offers some much-needed clarity - suggesting that how fit you are may be more important than what you weigh when it comes to living a long, healthy life.
As ever, please talk to your doctor or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle, especially if you are under treatment. Links to all studies at bottom of page.
What Was Studied?
The researchers reviewed 20 long-term studies from around the world, involving almost 400,000 adults. They looked at two major health outcomes: all-cause mortality (death from any cause) and cardiovascular disease (CVD) mortality. Each participant’s Body Mass Index (BMI) and cardiorespiratory fitness (CRF) were measured. Fitness was assessed via a VO2peak test - a rigorous evaluation of how well the body uses oxygen during exercise.
Participants were divided into six categories based on their weight and fitness levels, ranging from normal-weight and fit (the reference group) to obese and unfit.
The Core Findings
The study found that fitness level - not weight - was the more powerful predictor of long-term survival. In this meta-analysis, cardiorespiratory fitness was measured using maximal or VO₂peak exercise tests, such as treadmill or cycling tests. Participants were classified as either “fit” or “unfit” by placing them into the highest and lowest fitness groups within each study. This relative method allowed for consistent comparison across studies with different protocols and populations.
Generally, individuals were considered “fit” if they scored above the bottom 20% for age-adjusted CRF in their study group. This means that moderate fitness - achievable through regular activity - was enough to reduce health risks. Those in the lowest 20% were labelled “unfit” and showed significantly higher risks of death, regardless of body weight.
Fit individuals, whether they were normal weight, overweight or obese, did not have a significantly higher risk of dying than the normal-weight and fit reference group.
Obese but fit individuals had an 11% higher risk of all-cause mortality—but this wasn’t statistically significant.
Overweight and fit individuals were essentially at no greater risk than their leaner peers.
Unfit individuals, however, had alarmingly higher risks:
Normal-weight but unfit people had a 92% higher risk of death from all causes.
Overweight and unfit individuals had an 82% increased risk.
Obese and unfit individuals had double the risk of dying from any cause—and were over three times more likely to die from heart disease.
In essence, being physically unfit is a much stronger indicator of mortality risk than being overweight or even obese.
What This Means for Individuals
These findings lend strong support to the idea that you can be “fat but fit” - a person who carries extra weight but still maintains good cardiovascular health and mobility through regular activity. Just as importantly, they challenge the assumption that a “normal” BMI is automatically a sign of health. Without adequate fitness, even people in the so-called healthy weight range face higher risks of premature death.
Crucially, participants in the “fit” category didn’t need to be athletes. Most studies included people who ranked above the bottom 20% for fitness among their age group. That suggests that moderate, sustainable activity levels - like regular brisk walking, cycling or swimming - may be enough to significantly improve long-term health outcomes.
Fitness vs Fatness: The Bigger Picture
What makes this study particularly valuable is its inclusivity. It examined a more globally diverse population and included a higher proportion of women (33%) than earlier meta-analyses. Researchers also used improved statistical methods to avoid skewed results from overlapping data sets, making this one of the most reliable reviews to date on this topic.
Physiologically, it makes sense: physical activity helps regulate blood sugar, lowers inflammation, improves cardiovascular function, and builds muscle mass. These changes all contribute to reducing health risks - often independently of weight loss. In fact, many participants were able to gain these benefits even if their BMI stayed the same.
What’s more, the analysis found that fitness helped offset short-term mortality risks more significantly than in long-term follow-up periods. This might indicate that boosting your fitness now could yield relatively quick health benefits - even if sustained effects depend on maintaining that activity over time.
Rethinking Health Goals
Public health messaging has long focused on weight loss as the primary goal for reducing disease risk. Yet, weight-loss-only interventions often fail over time, with many people regaining the weight they lose within a decade. This repeated cycle can be physically and emotionally exhausting, and often doesn’t deliver lasting health improvements.
This study points to a more inclusive and sustainable strategy: focusing on physical fitness as a health goal, regardless of weight changes. Even modest improvements in fitness can drastically reduce your risk of heart disease and early death, especially if you’ve been largely inactive.
A Few Caveats
As compelling as these findings are, there are a few limitations worth mentioning:
BMI is a rough measure and doesn’t distinguish between fat and muscle or where fat is stored. It also doesn’t reflect the full picture of metabolic health.
The study population, while more diverse than past analyses, was still mostly male (67%) and largely based in high-income countries. Future research needs to include a broader range of ethnicities and socioeconomic backgrounds.
Being fit doesn’t guarantee perfect health. High BMI is still linked to conditions like type 2 diabetes and joint problems. But fitness appears to strongly mitigate the biggest risks, especially those related to heart disease.
Final Thoughts
The takeaway? Fitness really does matter - perhaps more than we previously thought. This landmark study adds to growing evidence that regular physical activity can dramatically lower your risk of early death, even if the number on the scale doesn’t change. While weight management might still play a role in overall health, it’s not the only path to wellbeing.
For many, a shift away from a weight-centric view of health towards a focus on movement and vitality could make healthier lifestyles feel more accessible, more enjoyable and more achievable. So if you’re working on getting more active, take heart: every step you take counts - not just for your weight but for your life. We take a similar approach with diet - for those who want to reduce their weight - a focus on nutritional excellence before caloric restriction.
Changing health for the better is about progress, not perfection, and even small changes can have a powerful and positive effect on health. For most people, improving health is about finding motivation and prioritising self-care - with an ultimate goal of taking action. If you want to take effective and targeted steps that fit into your unique lifestyle and circumstances, The Whole Health Practice is here to help.
Whether your interest is healthspan and longevity, to beat chronic illness or to enhance your mental health and well-being, our consultations and programs deliver results that are tailored to your needs.
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Alastair
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Weeldreyer NR, De Guzman JC, Paterson C, Allen JD, Gaesser GA, Angadi SS. Cardiorespiratory fitness, body mass index and mortality: a systematic review and meta-analysis. Br J Sports Med. 2025 Feb 20;59(5):339-346. doi: 10.1136/bjsports-2024-108748. PMID: 39537313; PMCID: PMC11874340.
Other
Gaesser GA, Tucker WJ, Jarrett CL, Angadi SS. Fitness versus Fatness: Which Influences Health and Mortality Risk the Most? Curr Sports Med Rep. 2015 Jul-Aug;14(4):327-32. doi: 10.1249/JSR.0000000000000170. PMID: 26166058.
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