The most common fallacy I see over and over again is the assertion that weight loss (or gain) is all a simple equation of calories in versus calories out. The simplicity of this concept is certainly tempting, but this is simply not true. Our body is far more complex than this teeter-totter equation.
Consider this: each second around 400 billion chemical reactions are occurring in your body. Each of those processes requires co-factors, chemicals that assist with these reactions. Some of these co-factors are made internally but many of them must be acquired from outside of ourselves, generally through our diet. Co-factors in our diet are the vitamins, minerals and phytonutrients we consume in our food. The food we ingest acts as a message to our body. When we eat nutrient-dense foods, our bodies are providing with all the necessary cofactors to break down that food and turn it into energy. When we eat food that lacks micronutrients (vitamins, minerals and phytonutrients), our body turns it into glucose but then lacks the co-factors necessary to complete the chemical reactions required to process that glucose into energy.
Our bodies’ being efficient above all else will then store the glucose, preferentially in the form of glycogen for later use. Then, when our blood glucose levels get low, the body turns this glycogen back into glucose to maintain our energy levels. Our glycogen stores function as our bodies’ short-term storage, allowing us to have energy throughout the day even when we are not actively consuming food. But, when we are ingesting enough food that our glycogen stores are full, our body then diverts the excess glucose to long-term storage in the form of adipose tissue, aka fat. Of course, weight gain is probably one of the less deleterious side-effects of eating nutrient-void food. You are also denying your body the nutrients it needs to keep you healthy and happy (yep—neurochemistry is dictated by diet too).
Another component of weight gain/loss is that the body needs to maintain a relatively consistent range of glucose in the blood. Eating well-balanced meals, containing adequate protein, fat and fiber, allow for a controlled release of glucose into the bloodstream. Refined carbohydrates, excess sugars and meals lacking protein, fat or fiber will all lead to an immediate spike in blood sugar and the urge to eat more of the same again soon, perpetuating the cycle.
An excess of blood glucose will also signal the body to store some as glycogen and a deficient will signal the body to convert glycogen back into glucose and release it. Every cell has insulin receptors that escort glucose from the blood into the cell and the number of receptors is dependent on the cell’s environment. If the body is constantly flooded with glucose (from a diet high in glycemic foods like refined carbohydrates and sugars), cells reduce the number of insulin receptors since they are perceived as unnecessary (with all this glucose floating around the cells think there will be no threat of not getting enough). Consequently, with the lack of adequate insulin receptors, glucose cannot be absorbed as quickly and builds up in the blood. The body perceives this as a threat and unnecessarily stores the glucose as glycogen and fat. Conversely, when we have low blood glucose levels, such as when we do not eat breakfast or when we drink alcohol, our bodies freak out and send a hormone response signally that we are in a starvation situation and that all incoming glucose should be stored as fat, because who knows when we’ll have access to food again.
So sure, the number of calories you eat does mater. And the calories you burn during exercise also do mater. But, as you approach your daily eating habits remember that nutrient-dense foods are the only ones that your body can readily turn into energy. Nutrient-void foods cannot be processed and will have to be stored until enough nutrients are consumed to deal with them—so you better balance that Big Mac with a lot of kale salads! Also, the time of day you eat does matter. Do eat breakfast to stabilize your low blood glucose level from the night and eat consistently throughout the day, consuming well-balanced meals and snacks that will not cause the glucose in your blood to skyrocket.
And remember, nutrition really is very simple. Just eat whole foods, consume a balance of fat, protein, carbs and fiber and eat consistently and sensibly throughout the day. Take care of your body and your body will take care of you.