Physical Fitness is an Independent Predictor of Body Weight

As a large European study with 2,056 healthy adults around age 50 shows, physical fitness, i.e. cardiorespiratory* fitness and physical activity influence body weight independently of each other and in varying degrees. There is a particularly strong association between fitness and the waist-hip ratio and/or body mass index** (BMI) both in men and in women. The research team led by the German Institute of Human Nutrition (DIfE), a partner in the DZD, and the Institute of Metabolic Science of Addenbrooke’s Hospital, Cambridge, UK has now published its findings in the journal Obesity (Wientzek, A. et al.; 2013)***.


Studies have long indicated that there is a relationship between the degree of physical activity and the occurrence of obesity. In most studies, however, the data on physical activity is not based on current measurements, but on self-reports of the test subjects. These are often flawed and can thus contribute to distortion of the study results. Moreover, cardiorespiratory fitness also plays a role in body weight. Generally it indicates how well breathing and blood circulation are able to supply the body with oxygen. Fitness is relatively stable over years and is influenced by the degree of physical activity performed in the past and also by genetic factors.
To learn more about the relationships between physical activity, fitness and body weight, the scientists carried out a large-scale European observational study. In this first-time study they determined the physical activity and fitness of the study participants by means of clinical measurements. Approximately 200 German, British, Danish, Greek, Dutch, Italian, Spanish, French, Swedish and Norwegian study participants were respectively recruited from the European Prospective Investigation into Cancer and Nutrition (EPIC)****.

Four-day fitness test
The researchers determined the fitness of the subjects by means of a simple, clinically monitored fitness test. The physical activity was recorded using a heart rate and movement measuring sensor which the subjects wore on their chests for a minimum of four days. Both measurements were repeated after four months to confirm and refine the data. The study showed that the better the participants’ fitness scores, the lower their waist-hip ratio and/or BMI. In addition, in women there was a fitness-independent and somewhat weaker relationship between the currently measured physical activity and the studied markers for body weight. In men, this relationship was only significant for the BMI.
"What is striking about our results is that exercise and fitness not only affect body weight independently of each other, but that physical fitness plays the greatest role for body weight and body fat distribution,” said Angelika Wientzek, lead author and epidemiologist at the DIfE. "Being physically fit and maintaining this fitness appears particularly important to prevent obesity. This is particularly true for men, in whom occasional physical activity only slightly affects body measurements,” added Heiner Boeing, head of the Department of Epidemiology at the DIfE.
 Background information:
 *Cardiorespiratory fitness: Generally it indicates how well breathing and blood circulation are able to supply the body with oxygen.

 **The equation for the calculation of the body mass index (BMI) is: body weight in kg/height in m². The BMI helps classify the body weight in underweight, normal weight and/or overweight. The equation for the waist-to-hip ratio (WHR) is: WHR = waist circumference/hip circumference. The waist is measured at the level of the navel and the hip at the widest point. The WHR provides an answer to the question where the fat deposits are, whether there is more abdominal fat or more around the hips. If the WHR in men exceeds the cut-off value of 1 or in women the cut-off value of 0.85, too much fat is deposited at the abdomen, which increases the risk for cardiovascular disease or type 2 diabetes.

 ***Wientzek, A. et al.; Obesity 2013; doi: 10.1002/oby.20530
 Cross-sectional associations of objectively measured physical activity, cardiorespiratory fitness and anthropometry in European adults.
Link to journal publication 

 ****EPIC: European Prospective Investigation into Cancer and Nutrition. The EPIC study is a prospective study that investigates the relationships between nutrition, cancer and other chronic diseases such as type 2 diabetes. Twenty-three administrative centers in ten European countries are involved in the EPIC study, which has a total of 519,000 adult-age participants.
 The Potsdam EPIC study with more than 27,000 participants is part of the EPIC study.