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Losing Weight Does Not Equal Physical Fitness

Published: 2010-03-29 - Updated: 2013-06-06
Author: Matt Denos, PhD

Synopsis: Considering the rise in obesity and obesity-related surgery a study looks at the correlation of weight loss and physical fitness.

Main Digest

As the obesity rate climbs throughout the world, surgical intervention has become a viable option for more people.


Considering the rise in obesity and obesity-related surgery, a study based in Ghent, Belgium intended to look at the correlation of weight loss and physical fitness.

The contention was fairly simple. If obese patients led a sedentary lifestyle prior to gastric bypass surgery, would large-scale weight loss on its own constitute physical fitness? If not, would the addition of a training program assist in the goal? If so, would training be a reasonable option considering morbid obesity and the endurance and strength required to train? Investigating the effect of the large-scale weight loss on physical fitness was the main focus of the study (Stegen and colleagues) at University Hospital Ghent.

How was the study organized

Based on certain criteria, 19 bariatric bypass patients were recruited for the study. In order to determine levels of physical fitness following surgery, the trial consisted of two groups. One group followed an exercise training plan (training group) and the other group did not (control group). The study took place over a period of 4 months following surgery. Patients were allowed to choose the group they wanted to join. Both groups experienced extensive pre-surgery and post-surgery tests and measurements.

What training program did patients follow

Each patient in the training group was guided individually through the work-out program. Exercise consisted of training three times a week for 12 weeks. Patients trained for 75 minutes including a 10 minute cool-down. Their training included a cardio warm up for ten minutes. Twenty five minutes was given for strength training while endurance training lasted 30 minutes. The training took place in the four months following bariatric bypass surgery.

What variables were measured to determine success

Weight, BMI, waist and similar measurements typical for gaging physical factors were included. Dynamic and static muscle strength was also accessed. Patients performed functional capacity tests measured before surgery and at the end of the 4 months to compare statistics. For example, one area of measurement was a 6-minute walking distance. The in-depth tests and measurements patients underwent were used for purposes of comparison in order to determine results.

What additional challenges to physical fitness did both groups share

First, breaking the cycle of obesity posed a big challenge. Patients had to overcome unhealthy patterns embedded in their lifestyles. Next, obstacles of the procedure of bariatric bypass surgery presented challenges. For instance, morbidly obese patients experienced post-operative large-scale weight loss but some of that weight was fat and some of it was fat-free mass. About 30-35% of weight lost in the first six months following surgical intervention was fat-free mass. Loss of that muscle mass contributes to less strength. In addition, the nature of bariatric bypass surgery tends to prevent protein from absorbing into the body. Less protein can also cause less muscle strength.

Was there improvement in tests and measurement statistics

Both groups experienced decreased static muscle strength measured by hand-grip. The training group had significantly better numbers than the control group. The control group presented reduced dynamic muscle strength. They experienced a 16%, 36% and 39% loss of their quadriceps, biceps and triceps strength respectively, while the training group experienced no reduction. In addition, in the training group biceps and triceps kept the same muscle strength while quadriceps (72%) and hamstrings (27%) revealed an increase in dynamic muscle strength.

Considering ability to perform daily tasks, both groups improved numbers in the distance covered in the 6-minute walk. Functional capacity in an activity called "sit-to-stand" improved for the training group but not for the control group. The amount of weight loss, waist size and change in BMI showed similar improvement for both groups.

What do the results indicate

As Dr Stegen explains, findings from the study underscored some commonly known facts. For example, all morbidly obese patients participating in the study benefited from weight loss. On the other hand, losing large amounts of weight is not an indicator of physical fitness. It often has the opposite effect. Loss of mass includes muscle mass leading to reduced strength. Less strength often prohibits activity leading to a more restricted lifestyle.

Results for the training group noted measurable success. When morbidly obese patients added a training program during the 4-month period after the bariatric surgery there were indicators linked to physical fitness. Training kept muscle strength from decreasing and some patients actually improved strength in some muscles.

Did results support an exercise training program

The data from the study underscores the need for a resistance and endurance training program to ensure optimal results for patients after bariatric surgery. Gastric bypass patients lost large amounts of weight to improve over-all health. However, for patients who did not train, muscle strength did not improve. In contrast, patients who followed a resistance and endurance program 4 months after surgery not only succeeded in stopping deterioration of muscle strength, they actually started gaining strength in some muscles. A negative impact for obese surgical patients who did not incorporate an exercise training program was loss of strength in muscles. The findings from the study promote a training program following weight-loss surgery.


1. Elder KA, Wolfe BM. Bariatric surgery: a review of procedures and outcomes. Gastroenterology.

2. National Task Force on the Prevention and Treatment of Obesity. Overweight, obesity and health risk. Arch Interm Med.

3. Seres, L, Lopez-/averbe J, Coll R, et al. Increased exercise capacity after surgically induced weight loss in morbid obesity. Obesity (Silver Springs).

4. Stegen, Suanne et. al. Physical Fitness in Morbidly Obese Patients: Effect of Gastric Bypass Surgery and Exercise Training. Ghent University, Ghent, Belgium.

5. Telford, RD. Low physical activity and obesity: causes of chronic disease or simply predictors? Medical Science Sports Exercise

About The Author:Given his background in medical science, Matthew Denos, PhD, has a special interest in the field of fitness, obesity treatment, and weight loss programs. You can visit his site at:

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Cite This Page (APA): Matt Denos, PhD. (2010, March 29). Losing Weight Does Not Equal Physical Fitness. Disabled World. Retrieved September 23, 2021 from