December 4, 2024, 3:12 pm | Read time: 6 minutes
Fat but fit – and therefore healthy? Is that possible? This is exactly what scientists wanted to find out. Research has proven that being overweight can make you ill and shorten your life. But are people with a higher body weight generally unhealthier than people of normal weight or thin people? FITBOOK Editorial Director Melanie Hoffmann explains the surprising results of a recent study.
There seems to be an increasing number of efforts on social media to change the stereotype of what a fit person should look like. Overweight people show themselves doing strength training in the gym, cardio, or even dancing. Their aim is to show that they may not look like typical athletes but that they are sporty. However, the comments under such posts and videos prove that many people don’t really want to believe them. The assumption still prevails: If you don’t have beautifully sculpted muscles but one or two too many fat pads, you can’t be truly athletic. And must, therefore, be ill or on the verge of becoming ill. But are fat people automatically less fit and unhealthier than thin people?
A study published in the British Journal of Sports Medicine investigated what is more important for health – fitness or body weight. And provides interesting arguments for the debate described.
Overview
Body weight and health
It cannot be denied that body weight plays a role in health. Being underweight or overweight can not only cause acute complaints but also have long-term consequences. It is worth noting here that a study from 2005 provided evidence that being underweight could be more strongly associated with increased mortality than being overweight. The overweight test subjects analyzed did not even show an increased risk of death compared to those of normal weight.1
Probably not least because more and more people in “Western” countries are overweight or obese, the effects of high body weight are attracting particular attention. In various studies, scientists have already investigated the links between this and the development of various diseases and the risk of death. It is known that too much body weight can lead to metabolic disorders such as insulin resistance and diabetes, high blood pressure, cardiovascular diseases, and even strokes in the long term.
The current meta-analysis
But what if a person’s fitness is also taken into account in addition to their body weight? What do the correlations look like? A meta-analysis by the University of Virginia (USA) aimed to answer these very questions.
Previous research had shown that cardiorespiratory fitness is associated with a lower overall risk of death and the risk of death from cardiovascular disease in particular.2,3 The US researchers were therefore interested in the influence of cardiorespiratory fitness in overweight people compared to people of normal weight.
Methodology
To select the studies, the researchers used the search engines PubMed/Medline, Web of Science, and SportDiscus and filtered the papers registered there according to the following search terms:4
- Fitness
- Cardiorespiratory fitness
- Physical fitness
- Maximal oxygen consumption
- VO2max
- Maximum oxygen uptake
- Exercise test
- Maximum treadmill test
- Body composition
- BMI and body mass index
- Overweight
- Obesity
- Mortality
- Deaths
- Death
- Fatal
- Cardiovascular mortality
- Chronic disease
- Cardiovascular
- Metabolic
- Cardiorespiratory
- All causes of death
In this way, the scientists were able to access all the research papers in the aforementioned databases that dealt with fitness levels, body weight, health data, and deaths. They reviewed 2279 articles found through these search filters and finally selected 20 studies with data from a total of 458,784 subjects for their meta-analysis. 307,385 (67 percent) were men, and 151,399 (33 percent) were women. The age of the subjects was between 42 and 64 years, and the follow-up period of the analyzed studies was between 7 and 26 years.
Prerequisites for inclusion of a study in the analysis were:
- The study was published between January 1980 and February 2023
- It was a prospective cohort study5
- Cardiorespiratory fitness was determined using a maximal or VO2peak exercise test
- BMI was reported and measured directly
- The joint effects of cardiorespiratory fitness and BMI on all-cause mortality or cardiovascular mortality were analyzed
- The reference group was normal weight, fit individuals
Using established and standardized statistical methods, the researchers used the comprehensive study data to find out whether and what possible relationships could exist between fitness level, body weight, disease, and mortality.
The study results
The analysis showed that both overweight, fit people and obese, fit test subjects did not have an increased risk of death compared to the reference group (normal-weight, fit people). They were statistically no more affected by all-cause mortality or cardiovascular mortality than fit people with a lower BMI. In contrast, unfit individuals, whether normal-weight, overweight, or obese, had a two- to three-fold increased risk of death compared to the control group.
“Fitness has been shown to be much more important to mortality risk than obesity,” explained Professor Siddhartha Angad of the University of Virginia in a press release.6 “Our study found that obese, fit individuals have a similar mortality risk to normal weight, fit individuals and nearly half the mortality risk of normal weight, unfit individuals. Exercise is more than just a way to burn calories. It is an excellent medicine for optimizing overall health and can significantly reduce the risk of cardiovascular disease and death of all kinds in people of all sizes.”
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Classification of the meta-analysis
The analysis of the 20 studies now seems to dispel the prejudice that overweight people are generally unhealthier than people of normal weight. It encourages people who are struggling to lose weight to keep exercising in order to promote their health. It also provides arguments for people with a higher BMI who do not want to lose weight to continue exercising. And for people who are thin or of normal weight, the research findings show that exercise is about more than just appearance and a desired weight. Those who weigh less are not automatically healthier and should not give up exercise.
However, it should also be mentioned that the current study is a meta-analysis of earlier research. The scientists did not conduct the study themselves but analyzed the results of previous projects. Accordingly, they were unable to verify whether all the data was correct, for example.
The scientists themselves cite various limitations in their analysis documentation, including the fact that only English-language studies were considered for the analysis. The fact that the analyzed studies only used the body mass index to assess body weight is also seen as a weakness by the scientists. The BMI has long been the subject of controversy as an index value in this context.
It should also be acknowledged that there have been studies in the past that have come to a different conclusion. For example, a 2021 study found that fit but overweight people had a higher risk of high blood pressure and potentially resulting cardiovascular disease.7