Im Freezing! Why Gastric Bypass Causes Patients to be Cold

Body temperature is the result of your body generating and radiating heat. The body is adept at keeping its temperature within a narrow range even though ambient air conditions vary. A normal body temperature is 98.6 F. It is common during the period of rapid weight loss for bariatric patients to feel cold or chilled, even when their temperature reads normal.

People who experience the massive weight loss associated with weight loss surgery experience feeling cold for two reasons: loss of insulation and less energy generation.

Fat is a highly efficient insulator. Consider animals native to cold climates: for example sea lions and polar bears. They are loaded with insulation and thrive in cold climates. When gastric bypass patients follow the rules: eating protein and exercising, the weight lost can only come from fat or stored energy. In effect you are losing your insulation. Less insulation increases the likelihood that you will feel cold.

The second reason for feeling chilled is that the metabolic cell processes are not working as hard as when you were heavier; it takes fewer calories and less energy to maintain and move a smaller body. Think about using an electric mixer: if you are whipping egg whites for a meringue the mixer will do this task effortlessly. But use the same mixer to knead bread dough and it will become warm to the touch, it is working harder because it is moving more mass. The same thing happens with your body; the more mass it must move, the harder it works. As a result more heat is generated.

The body has two well-tuned mechanisms for regulating body temperature: sweating and shivering. What overweight person hasn't been embarrassed by a sticky bout of sweating at the most inappropriate time? Sweating is a mechanism for cooling your body when it becomes too hot inside. The body rids itself of excess heat by expanding the blood vessels in the skin so the heat may be carried to the surface. When this energy or heat in the form of sweat reaches the skin's surface it evaporates and helps cool the body.

Gastric bypass patients become more familiar with the second temperature regulator, shivering, as they lose weight. When you are too cold your blood vessels will contract reducing blood flow to the skin. The body responds by shivering which creates extra muscle activity to help generate more heat. If you allow your body to shiver it will begin to feel warmer. But this is also a good clue that it's time to put on a sweater or turn up the heat. I think most weight loss patients will happily wear a sweater - a sweater is much easier to shed than that insulation we've worked so hard to lose!

Most weight loss patients report that their body temperature regulates after their weight is stabilized, usually eighteen to twenty-four months after surgery. Keep in mind your body is rapidly losing weight and the rest of your body's functions are caught off guard when this weight loss begins. The body's thermostat needs time to catch up to the weight loss, and it will. Patients who incorporate exercise in their weight loss program experience less chilling than patients who do not exercise.