Is weight loss really as simple as a calorie in calorie out approach? Well, if you have ever tried dieting then you probably are aware that the answer to that question is no. While it seems very simple on the surface, eat fewer calories than you expend and you will lose weight, this approach does not take into account the complexity of our bodies. Honestly, if it was as simple as calories in vs. calories out, we would not be discussing the fact that obesity is so rampant in our society.
For about 30 years now the US government guidelines for nutrition, aka the Food Pyramid or more recently My Plate, have recommended a high-carb, low fat approach to dieting. What we have seen in those 30 years though has been a marked increase in obesity and obesity related disease. As of 2014, more than one-third (34.9% or 78.6 million) of US adults are obese. Further, obesity has more than doubled in children and quadrupled in adolescents in the past 30 years. (According to cdc.gov) Not only have they recommended a low-fat, high-carb approach but, they have always recommend cutting calories.
While I agree that calories are definitely a factor when it comes to body composition, they are not the only factor affecting body composition. You must consider that everything you consume has an effect on your body and that effect is far more complex than how much energy is in the foods you consume. (Calories are a measure of energy) At the most basic level you must consider the macro nutrients of the food. A carbohydrate has a much different effect metabolically than protein or fat. For instance, ALL carbohydrates, regardless of the source, are converted to glucose, blood sugar, in the body. On a higher level you must consider what I think are two VERY, if not the most, important factors; those factors are hormones and your gut health.
Hormones are your body’s chemical messengers. They travel in your bloodstream to tissues or organs. They work slowly, over time, and affect many different processes, including
Growth and development
Metabolism – how your body gets energy from the foods you eat
Endocrine glands, which are special groups of cells, make hormones. The major endocrine glands are the pituitary, pineal, thymus, thyroid, adrenal glands and pancreas. In addition, men produce hormones in their testes and women produce them in their ovaries. 
So, why are they important? Everything that you eat, drink, breathe, and come into contact with has, or can have, an effect on your hormone levels. Take for example insulin. Insulin is a hormone made by the pancreas that allows your body to use sugar (glucose) from carbohydrates in the food that you eat for energy or to store glucose for future use. Insulin helps keeps your blood sugar level from getting too high (hyperglycemia) or too low (hypoglycemia).
The cells in your body need sugar for energy. However, sugar cannot go into most of your cells directly. After you eat food and your blood sugar level rises, cells in your pancreas (known as beta cells) are signaled to release insulin into your bloodstream. Insulin then attaches to and signals cells to absorb sugar from the bloodstream. Insulin is often described as a “key,” which unlocks the cell to allow sugar to enter the cell and be used for energy.
What does all of that mean? If you have more sugar in your body than it needs, insulin tells your body to store it. First, in the liver, and then as fat. So, quite simply, if you are chronically over consuming foods that keep your blood sugar elevated then your body has a constant signal to store fat. Recall, I said above that all carbohydrates are converted to blood sugar/glucose. So if you are constantly consuming more than your body needs you WILL store fat.
Now, do I recommend a “low carbohydrate” diet based on the above? Well, that depends. If you are naturally lean and/or are an athlete you probably have no issue with your carbohydrate intake levels and may actually thrive on a higher carbohydrate intake. (Not My Plate levels but, normal levels) However, if you are overweight or obese you are more sensitive to carbs and should consider a lower carb lifestyle or targeted carbohydrate intake. (More on that later)
In part 2 of this post, I will discuss gut health and why it is important… stay tuned. http://www.nlm.nih.gov/medlineplus/hormones.html  http://www.endocrineweb.com/conditions/type-1-diabetes/what-insulin