Losing Weight and Physical Fitness After Weight Loss Surgery

As bariatric surgery becomes more commonplace as an answer to morbid obesity, a study in Ghent, Belgium investigated the relationship between losing large amounts of weight and physical fitness after the surgery. In an attempt to determine whether physical fitness improves following surgery, Dr. Sanne Stegen and associates, hoped to find answers that might provide links to breaking the cycle of obesity. The main focus of this 2009 study was investigating the impact of organized training on physical fitness following gastric bypass surgery. Another objective of the study was to consider the feasibility of morbidly obese patients participating in a strength and endurance program for the first 4 months after surgery.

For morbidly obese patients who seek relief of symptoms and a desire to become more physically fit, surgical intervention does result in large-scale weight loss. Weight loss reduces fat mass. However, 30-35% of the total pounds lost during the first 6 months after gastric bypass surgery consist of fat-free mass. In addition, the lack of protein absorption due to the nature of the procedure may attribute to less muscle strength. Could an exercise regiment prevent loss of muscle strength or even help patients gain more strength?

How was the study designed?

The study consisted of two groups. One group followed exercise training beginning four months after surgery, while the other group had no exercise mandate. Nineteen patients met the criteria to join the study. Each person was allowed to be either in the training group (organized on-going exercise program) or in the control group (surgical intervention only). Each group of patients underwent a battery of tests and measurements prior to surgery. The measurements were taken throughout the recovery process and at the conclusion of the 4 month study when tests were completed.

What was involved in the exercise program?

The patients in the exercise group benefitted from guidance by Master of Movement and Rehabilitation Sciences. The training sessions were individually supervised three times a week through 36 sessions. Ten minutes of cardio warm-ups, 25 minutes of strength training and 30 minutes of endurance training was completed in each workout. With a 10 minute cool down added in, the time for each workout was 75 minutes.

What were the results?

Following 36 weeks after the surgery both groups had similar weight loss, BMI and waist measurements. Weight lost by these patients consisted of pounds lost in fat mass and fat-free mass as well. Loss of pounds of muscle mass in all bariatric bypass patients resulted overall to lower dynamic muscle strength in some areas. That means that all patients became weaker. However, although exercise training could not totally prevent a decrease in fat-free muscle mass, the strength deficit of the training group was less dramatic. Despite fat-free muscle loss, the training group showed dynamic strength improvements. The benefit from training also proved that fat-free mass could be maintained. A positive indicator in weight loss due to surgical intervention shows less fat-free mass lost through the surgical procedure than fat-free mass lost by a very low calorie diet.

Dynamic muscle strength

The untrained patients experienced reduced dynamic muscle strength. Quadricep strength lowered by 16%; biceps were 36% less strong while triceps strength decreased by 39%. Taking a look at the training group showed different results. Interestingly, the exercise program kept biceps strength from dropping. Triceps and quads actually increased in dynamic muscle strength. In addition, hamstrings increased strength by 27%.

Static muscle strength

Both groups lost strength in static muscles, which was measured as handgrip strength. Four months after surgery the trained group lost 7% while the untrained group lost more than double that number, with an 18% loss.

Functional capacity

Both patient group numbers were analyzed on their ability to perform daily tasks. Statistics in function capacity prior to surgery and 4 months after surgery were measured. Actions such as sit-to-stand and a 6-minute walking distance were accessed. Both groups improved walking distance, but only the trained group increased numbers in their ability to rise to a full stand from a seated position within 30 seconds.

What is the practical application of these results?

The objective of finding links between post-operative weight loss and physical fitness was answered in the study. When morbidly obese patients experience large-scale weight loss through surgical intervention there are many benefits. However, none of them is physical fitness. Losing large amounts of weight does not equal physical fitness. In reality, loss of body mass will include fat and fat-free mass causing a negative impact on muscle strength.

The findings show that an exercise-training program on a postoperative patient group prevents muscle loss. When morbidly obese patients lost large amounts of weight and then added an organized work-out routine to the recovery process, they did see improvement in physical fitness. The study indicated that adding an exercise program could stop the decrease of strength in most muscles. In addition, some patients were able to actually increase strength in some muscle groups.

Based on the findings of the Stegen study, an endurance and resistance training program should be encouraged during the four months following surgical intervention. Dr. Stegen concludes that for morbidly obese patients, losing large amounts of weight will not improve physical fitness. But, for those who participate in exercise training, it is possible to become more physically fit.


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

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

Matthew Constantin, PhD, is enthusiastic about all that is happening in the research field of obesity treatment, nutrition and diet. Having a medical background, Matthew enjoys writing articles that present current scientific findings in the topic of weight loss. He often posts reviews about best weight loss diets and offers coupon codes for Medifast diet program.