So far in this series I have covered the fundamental science of weight loss.  Put simply, if a person is able to consume fewer calories than they burn then they will lose weight, and calories are burned through a combination of exercise and basal metabolic rate. Unfortunately in the real world consuming fewer calories than are burned can be a difficult proposition, this is why only 5% of people achieve long term weight loss through diet and exercise alone.

In this post I will attempt to explain the role of bariatric or weight loss surgery, what it does, how it works as a tool, and how it can help people to achieve long term sustained weight loss.

Bariatric surgery works on the calories consumed side of the equation.  The three most popular surgeries, gastric bypass, lap band and sleeve gastrecomy, all make people less hungry and consume fewer calories.  The average number of calories consumed after gastric bypass surgery (~1000 per day) is slightly less than after lap band surgery (~1200 per day).  In addition gastric bypass causes people not to absorb approximately 300 calories per day of the food they do consume.  These two factors probably account for the faster weight loss seen after gastric bypass compared to lap band surgery.

By reducing calories consumed, weight loss operations make it easier to achieve the calorie deficit necessary to lose weight.  However this also explains why they are only a tool for weight loss, and not a magic solution on their own.  People with a low metabolic rate who are not able to exercise may not lose weight even when consuming only 1000 calories per day.  Also when people lose weight rapidly after surgery they tend to lose muscle and consequently drop their metabolic rate.  This can then lead to reduced weight loss, or late weight regain.

Avoiding these outcomes after bariatric surgery requires a holistic approach to weight loss.  Here at Oregon Weight Loss Surgery we routinely measure patients body compositions and metabolic rates.  Low metabolic rates can be identified and treated before they become a problem.  A commitment to regular vigorous exercise is also very important to an optimal long-term outcome.  We work with physical therapists who can help people develop a safe and effective exercise routine that they can easily incorporate in to their daily lives.

This is the last post in this series about weight loss.  Please feel free to post comments or questions below, or for people interested in getting more information about weight loss surgery click on this link to sign up for one of our free information seminars.