The art and science of weight loss, part 1

In this series of posts I plan to cover the fundamentals of weight loss, the effect of surgery, and the other relevant issues.  Although many people know the fundamentals, they are an important background to how surgery works and how to maximise weight loss and so I will recap them first.  I want to present a framework to show how the human body gains or looses weight, why we can struggle to loose weight, how weight loss surgery can help, and why weight loss surgery is not a magic bullet.

One pound of fat contains 3500 calories.  In other words, if a person consumes 3500 more calories than they burn, they will gain a pound of fat.  On the other hand, to loose a pound of fat, one must burn 3500 more calories than one consumes.  If we look at weight loss over time, a safe rate of weight loss of one pound per week requires a daily deficit of 500 calories (500 x 7 = 3500).

This can be expressed mathematically as calories consumed – calories burned = -500.

Still with me?

Calories burned is actually made up of our resting metabolic rate (RMR) + calories burned in activities.  Resting metabolic rate is the calories our body uses to stay alive (breathing, making the heart pump, thinking etc).  We also burn calories when we do extra activities (e.g. building a fence, running, circuit training).

Therefore to loose one pound per week it is necessary to either consumer 500 fewer calories per day, expend an additional 500 calories per day through exercise, increase our metabolic rate by 500 calories, or some combination of the three.  None of these three things are easy, but all are possible.  Weight loss surgery is a tool that can help with reducing calories consumed, but attention to the calories burned is also important for reasons that I will discuss.

Next post I will cover reducing calories consumed, and increasing calories burned through activities.  Later I will discuss why resting metabolic rate is important and the effect of surgery.