A few days ago, scientists attending an academic conference presented a new formula which is proposed to accurately predict how many calories and how much exercise one must do, over a period of months or years to successfully lose weight. Prior to this, many believed that weight loss was a gradual process that was completely dependent on calculating calories in versus calories out. For example, if you routinely consume 1200 calories a day, you will comfortably lose ½ – 1kg a week.
Now, anyone who has successfully lost weight, who works in the field of weight loss or who is currently trying to lose weight, will know that this is not the way things work. In real life, sometimes you will lose weight, and sometimes you will not, and sometimes this can have nothing to do with how many calories you have taken in, nor how many you have been burning via exercise, rather it has to do with changes to metabolism over time. To make this clearer, try and imagine that your body is like a machine, with each cell representing an engine that can burn fuel or in this context, calories. When someone is overweight, chances are the cells are not burning their fuel efficiently and as a result; a reduction in fuel intake from taking in fewer calories from food will result in weight loss. Once though a certain amount of weight is lost, whether that is 5kg or 10kg or 20kg, the cells will begin to work more efficiently, which also tends to mean that they need more calories to continue to burn energy as efficiently as they once did. In the case of weight loss, this may also mean that people may need to eat more calories to keep losing weight. Or if someone has been used to consuming a high number of calories and has still been losing weight, they may need to further cut back on calories to continue to get the weight loss results they are looking for.
Basically what this means if you are trying to lose weight is that adjusting the number of calories you are having regularly is crucial for long term weight loss. Sure a 1200 calorie plan may see you take 5 or 10kg off, but once weight loss slows down, you are likely to need 100-200 calories more to see continual weight loss, simply as 1200 tends to be the lowest any human can go calorie wise without negatively impacting metabolic rate.
When it comes to training, it also means that you can do too much. If you are only consuming 1200 calories and then burning 600-800 with 2-3 hours of training a day, your weight loss too may slow as the differential between calories in and calories out is simply too great.
So, the take home message today – if you are trying to lose weight, adjust your calories when you experience a weight loss plateau and check that you are not overtraining for the amount of calories you are taking in. As a general rule of thumb, add an extra 100 calories for every hour of exercise that you do and you will be on the right track.