I definitely believe in the health benefits of a diet low in carbohydrates. I try to center my meals around protein content and I include enough healthy fats to make the meal taste decent. I also like to throw in a decent amount of veggies when I can so I have alot of calorically sparse fibrous stuff to fill me up with. I find that such a diet shrinks my waistline, gives me sustained energy, and decreases inflammation throughout my body.
There are dozens of theories why reducing carbohydrates leads to a host of positive beneficial effects and many of these revolve around the hormone insulin. I won’t get into all these theories. I would like to mention a recent clinical study however which may have put one more piece of the puzzle together to explain why high carbohydrate intake seems to lead to undesirable physical effects.
The study* used ten male subjects with normal body mass indices. The subjects all had the same normal breakfast but for lunch they either had a shake consisting of fat, protein, carbohydrate, or water. All the shakes were designed to have similar taste(except the water which tasted like water). This went on for four days and each subject took turns as to which lunch shake they would have.
When water was consumed, cortisol levels were seen to drop. This drop was simply the normal drop that happens in later morning (since cortisol levels are highest in the morning and then drop). With protein and fat lunch consumption the normal cortisol dip was also seen. However, when the pure carbohydrate lunch was consumed cortisol actually rose considerably and stayed up relative to the other lunches for two hours.
Cortisol is the bodies stress hormone and it serves to promote fat gain – particularly visceral fat gain. This condition also sets the stage for metabolic syndrome which is connected to glucose intolerance, high blood pressure, inflammatory diseases, and blood lipid irregularities. The risk for heart disease and diabetes is high in individuals with this condition.
What do we take home from this? Well, there definitely appears to be a correlation between a carb meal and cortisol elevation. This could indicate one pathway responsible for a connection between high carbohydrate intake and obesity. However we don’t know what the effect of mixed macronutrient meals might be, nor do we know what happens to cortisol during chronic carbohydrate intake. More research needs to be done before any definitive conclusions can be drawn.