Why Do You Feel Cold When You Lose Weight?

Eating too little can give you the chills.
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Achieving a healthy weight improves your quality of life and makes you feel good about yourself. But you may notice you have less tolerance for cold environments and always reach for a cardigan or jacket -- even when others seem comfortable. Gradual weight loss and realistic body fat goals can help protect you from feeling chilled as you drop pounds.


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Less Body Fat to Insulate You From the Cold

Low body fat levels help you look lean and may improve sports performance, but you need some essential fat -- at least 10 to 12 percent for women and 2 to 4 percent for men -- to support basic function. This essential fat pads your internal organs, absorbs vitamins and acts as insulation. Fat cells also release energy when they sense cold temperatures, which helps keep you warm.


When you shed body fat, you literally lose insulation, so you may feel more sensitive to a dip in temperature.

Extreme Calorie Restriction Slows Your Metabolism

Eating too few calories in an effort to lose weight might cause cold intolerance, even if you haven't experienced large drops of body fat or weight. You need to consume a certain number of calories to produce body heat. When you eat too few calories, your metabolism slows down to save energy. Calorie restriction causes a reduction in daytime and nighttime core body temperature, according to a small study published in Aging in 2011.


Too drastic of a calorie reduction may also affect your hormone production, especially thyroid hormone. When your body produces too little thyroid hormone, it can make you feel cold. If you're skipping meals or skimping on carbohydrates, you may have low insulin levels, which can also lower your body temperature.


You risk decreasing your metabolism and negatively affecting hormone production when you regularly consume fewer than 1,800 calories as a man or 1,200 calories as a woman daily. Instead of drastically reducing calories in hopes of losing weight quickly, aim for a gradual rate that is more manageable and sustainable for the long term. Use an online calculator to determine how many calories you burn regularly, then subtract between 250 and 1,000 calories to determine how many you should eat to lose between 1/2 and 2 pounds per week. Always make sure that the deficit still allows you the minimum number of calories to keep your metabolism revved. This slower rate of weight loss makes it less likely you'll experience nasty side effects such as chills, nutrient deficiencies and muscle loss.

Nutrient Deficiencies and Feeling Cold

When you're trying to lose weight, you are focused on taking in less food -- and may be unknowingly denying yourself essential nutrients such as iron, vitamin B-12 and folate. A deficiency of these nutrients is defined as anemia -- a condition in which your body has trouble producing enough red blood cells, which carry oxygen to your internal organs and bodily tissues. If your coldness is accompanied by feeling grumpier than usual, being overly tired or having brittle nails and regular headaches, you might talk to your doctor about your diet and the possibility of doing blood tests to evaluate your nutritional status.

Make sure you eat foods rich in these nutrients, even when you're trying to lose weight. Go for red meat, liver or lentils for iron; eat meat, poultry, fish and dairy to get B-12; and grab some dark green vegetables, chick peas and fortified grains for folate.

Following a weight-loss plan might trigger anemia, even if you follow a healthy diet. For example, women who have heavy flows during menstruation may become iron-deficient.

Possible Medical Cause for Feeling Cold

In some cases, your cold intolerance only coincidentally corresponds with your weight-loss plan. Feeling cold for no apparent reason might signal the presence of a blood vessel disorder, hypothyroidism or dysfunction in the hypothalamus, a part of the brain that acts as the body's thermostat. If you're sure you're eating enough of the right foods and have a normal body fat level, you might want to consult with your physician to make sure you don't have an underlying condition.


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