I have seen a bunch of people lately who are trying to lose weight or change their body composition. They have a number for how many calories they think they need to eat each day. They could have used an online calculator to get this number. They could have asked someone else how much they eat. Or, they could have just pulled it out of the air.
Each of our bodies has a certain number of calories that they need in order to function. Your Resting Metabolic Rate (RMR) is the amount of calories your body needs to perform all of its functions when you are at rest. This is the minimum number of calories your body needs each day. On top of RMR you add calories for other activities you do during the day including sitting at your desk working, walking around, and working out.
If you want to lose weight, you should consume fewer calories than you expend. . . within reason. If you want to lose a pound a week, you should eat 500 calories less per day than you take in.
Remember, food is energy. There is a limit to the amount of calories that you reduce. If you reduce the calories too severely, your body will start conserving the food – and energy – that you give it through eating. One of the ways this happens is when people consistently start eating less than their RMR. When this happens, your body goes into conservation mode. An example will help explain this concept. Sam has an RMR or 1900 calories and a total of 2800 calories expended throughout the day. He consumes 1500 calories per day. This means that on a daily basis, Sam has a deficit of 1300 calories. Since there are about 3500 calories in a pound, Sam should lose 2.6 pounds per week (1300*7/3500=2.6). Sam lost weight at first. But, recently Sam hasn’t lost any weight in weeks. He is frustrated. Very frustrated. What is going wrong?
What is wrong is that his body is saying “Sam is only going to give me 1500 calories but ask me to do 2800 calories of work. I’m going to start slowing all my metabolic processes down so I can conserve the calories he does give me.”
When I have clients like this, I explain this to them and explain that they have to eat more. Yes, eat more. In these instances you have to eat more to lose weight. It may take some time for your body to realize that you are going to fuel it properly. It may decide to put on some weight at first. Once your body trusts that you are going to fuel it properly, you will start losing weight again.
I know it seems counterintuitive to eat more to lose weight, but if you have drastically reduced your calorie intake and are not losing weight, ask yourself if perhaps you have cut your intake too much.
If you want to know how many calories your body needs, you can get an estimate using some calculations (I have a blog on how to do that here). You can get your RMR measured using special equipment called a metabolic cart. There are also the MedGem and the BodyGem.
If you have been trying to lose weight and are stalled, I would encourage you to look at how many calories you need, how many you are taking in, and decide if you have reduced you calories too far.
If you have had success losing by eating more, let me know.

