What is Metabolism and How to Make It Work for Your WLS

February 20, 2017

Metabolism. We have all heard that word at some point when discussing weight “He can eat whatever he wants; he must have a good metabolism” or “I have a slow metabolism, it doesn’t matter what I eat, I can’t lose weight.” But what is metabolism? How does this affect weight maintenance, loss, and gain? What can be done to ensure as an efficient metabolism as possible? How is metabolism affected after weight loss surgery?

The Definition of Metabolism

Metabolism refers to the process by which your body converts what you consume (food and beverage) into energy to be used or stored. It influences your basal energy needs, also known as your basal metabolic rate (BMR). This refers to the energy that your body expends at rest in a neutral environment. BMR is influenced by a number of factors: age, sex, and body composition (lean body mass versus fat mass). Age and sex are difficult to change. However, body composition can often be tweaked through proper diet and exercise, although some body composition may also be attributed to genetics.

Exercise is especially important – exercise not only burns calories, it also builds muscle. Muscle is our most metabolically active tissue, so the more you have, the more efficient your body is at burning calories, even at rest. Thus, adding in strength training along with cardiovascular exercise helps to build more muscle, increasing your body’s ability to burn calories, both in action and at rest.

Examples of good strength training exercises include weight training (machines and free weights), resistance bands, and using your own body weight (such as push-ups, pull-ups, squats, etc).

Weight imbalance is most commonly linked to a problem with calories taken in versus calories expended. However, in obese individuals, there may also be a degree of metabolic resistant obesity, in which the body actually works against weight loss by decreasing the metabolic rate and increasing hunger hormones when a certain degree of weight loss has been achieved, leading to decreased overall weight loss and even unsuccessful weight maintenance. This is why some people who lose weight initially on traditional diet and exercise regimens, find it difficult to lose much more and may gain the weight back after a period of time.

Weight loss surgeries impact the degree to which your body can eat, hold and absorb, but also helps to prevent the body from decreasing the individual’s metabolic rate with weight loss, modifies the way the body metabolizes fat, and also modifies hunger/satiety hormones to better aid in weight loss and weight maintenance.

Metabolism and Life After WLS

So how does this all tie into life after weight loss surgery? Diet-wise, protein is an important piece to the puzzle. Protein should be the most important part of your diet post surgery to help not only with the healing process and keeping your immune system healthy, among other important functions but, as noted above, it also helps to maintain your lean body mass (your muscle). Again, the more muscle you have, the more effective your body is at burning calories, thus boosting your metabolic rate during activity and at rest, and aiding in overall weight loss.

Great sources of protein include lean meat, poultry, fish, eggs, low-fat dairy, nuts and seeds, beans and legumes, and certain grains such as quinoa. This, along with a diet rich in plant-based foods, such as fruits, vegetables, whole grains, nuts and seeds, and healthy fats helps support a healthy weight and body composition (i.e. more muscle mass, less fat mass).

Unfortunately, outside of the thermic effect of food (the amount of energy it takes, above the BMR, to digest and metabolize food), there are no foods that actually increase metabolism, as some non-evidence based sources will have you believe. Weight loss surgeries do impact the way you digest certain nutrients, especially fat and carbohydrates, so it is important to follow a diet that is low in simple carbohydrates, high in complex carbohydrates (i.e. fiber from fruits, vegetables, and grains), and utilize more healthy fats (i.e. avocados, plant-based oils, nuts and seeds and cold water fish). A diet centered around protein and low in calories is important to life after weight loss surgery, as calories in versus calories out is still vital to success.

Metabolism and Exercise

Adding exercise to your daily regimen is also important – current recommendations are 150 minutes per week, so that equals out to 5 days a week, for 30 minutes. Cardiovascular exercise is important, but also remember to add in the strength training. Often 2-3 days a week, for 20-30 minutes a day is all it takes to improve muscle tone and strength, and build more muscle. Checking with your doctor to ensure that exercise, both cardio and strength training, is important before starting any exercise program.

Physical trainers can also be very helpful, in that they can give you a regimen that works for you, taking into account any medical issues, and help you get the most out of your workout. They can also ensure that body mechanics are correct, which leads to less injuries and better health and wellness overall.

As you can see, there are many mechanisms in place through weight loss surgery that act as a tool in weight loss over time and help change the metabolic system. However, it is important to remember that it is still very much up to the individual as far as the degree of success they will have with weight loss surgery. Diet and exercise are still key to long term success and helping to make your metabolism as efficient and effective as possible!

keri layton


Keri Layton RD, CSO, LD has a strong background in providing medical nutrition therapy for many nutrition-related health issues, including diabetes, renal disease, heart health, nutrition support, as well as general nutrition and weight loss. For the past three years, Keri does private nutrition consulting as well as bariatric consulting with Bariatric Dietitian Services.

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