This simple equation is touted as the key to obesity. It is deceptively simple and absolutely untrue. The underlying assumptions behind this equation are to blame. Let’s explore them.
Assumption 1: Calories in and calories out are independent of each other.
Decreasing calories in results in a direct drop in calories out. The end result is minimal weight loss. We have known this for a while now, nearly a 100 years to be exact. A study was carried out in 1919 at the Carnegie Institute of Washington. Volunteers were given a diet 30% lower in calories in than their usual diet. The participants experienced a 30% drop in their energy expenditure!
This is what happens when calories in are reduced.
- Calories are needed to heat the body, when fewer calories are available body heat is reduced, hence one constantly feels cold.
- Calories are needed to pump blood, so when calories in are reduced the heart rate slows down and stroke volume is reduced.
- Calories are needed to maintain blood pressure, when enough calories are unavailable, blood pressure goes down.
- Calories are needed to maintain regular brain function, when calories in is reduced, lethargy and inability to concentrate are induced.
The body reduces energy expenditure as a defence mechanism, if it didn’t then the person in question would likely die.
Assumption 2: Basal Metabolic Rate is Stable
It is assumed that the body’s energy expenditure is maintained at a constant rate, except for exercise, whereas this just isn’t true. Measuring energy in is easy, but measuring energy out is quite complicated. Total energy expenditure can go up or down by 50% depending upon caloric intake and other factors.
Assumption 3: We exert conscious control over calories in.
Eating is a deliberate act, so we assume hunger plays only a minor role. However various hormonal interactions play a big part in when to eat and when to stop. We decide to eat based on hunger signals in the body triggered by hormones and then we decide to stop when we are full because of other hormones which signal satiety. For example, smell of fried food at lunch will make your mouth water, but the same smell after you’re stuffed will make you queasy.
Assumption 4: Fat stores are unregulated.
Every system within the body is tightly regulated. Growth hormone regulates growth in height. Blood sugars are regulated by insulin and glucagon among others. Testosterone and estrogen regulate sexual maturity and thyroid stimulating hormone and thyroxine control body temperature. Why then are we asked to believe that fat stores are unregulated? This has already been proven wrong. Leptin is the best known fat regulating hormone. If hormones regulate fat growth, then obesity is a hormonal disease.
Assumption 5: A calorie is a calorie
This statement implies that all foods can be reduced to their caloric value. Does a calorie of olive oil have the same metabolic response as a calorie of sugar? The answer is obviously no! Sugar will raise blood glucose levels and stimulate insulin release, olive oil will not.