When we get sick, our bodies undergo various physiological changes to fight off the cause of the illness and restore our health.
Among the many misconceptions surrounding illness and its effects on the body, the notion that we burn more calories when sick often emerges. But is there any truth to this claim? In this article, we will understand more about this and separate fact from fiction.
Do You Burn More Calories When Sick?
When sick with a fever, your body burns more calories as it raises your basal metabolic rate (BMR) to increase your temperature and enhance your immune response. So, having a fever means you burn more calories.
When sick without a fever, such as with the common cold, you likely won’t burn many extra calories. However, you may still experience a caloric deficit because your appetite is typically suppressed.
Basal metabolic rate (BMR) refers to the number of calories the body needs to perform essential functions at rest, such as maintaining organ function, regulating body temperature, and supporting cellular processes.
How Many Extra Calories Do You Burn With a Fever?
It’s difficult to determine exactly how many calories a fever burns since every individual is different.
When your body temperature rises by 0.5C or 1.0F above normal, your basal metabolic rate (BMR) increases by around 7%.
Let’s understand this by using an example to make it easier.
If a person has a BMR of 2,000 calories per day, a 7% increase due to a fever would result in an additional calorie burn of 2,000 calories multiplied by 0.07 = 140 calories per day.
Keep in mind that these calculations provide an estimate, and individual variations can occur.
The number of calories you burn at rest greatly depends on your body mass. Males tend to burn more calories than females because they have more muscle.
Do You Lose Weight When You Are Sick?
Yes, it is common to temporarily lose weight when you’re sick. This weight loss is primarily due to water loss, which will likely be regained later. However, if you’re eating significantly less than usual and/or running a high fever, it’s possible to lose actual body fat or muscle.
When you’re sick, you tend to eat less, resulting in reduced food intake and depleted glycogen stores in your muscles. Both of these factors contribute to a decrease in weight. Additionally, if you’re not careful about staying hydrated and replenishing electrolytes, sickness can lead to dehydration, causing further water weight loss.
In the case of a significant and prolonged caloric deficit, it’s possible to burn fat or muscle. However, during a short illness where you’re consuming an adequate amount of food, you should not experience significant losses of muscle or fat.
Should You Eat More When You Have a Cold?
Yes, it is generally recommended to eat a little extra when you have a cold. Some studies suggest that reducing calorie intake during illness can worsen symptoms and prolong the sickness.
Increasing your calorie intake may also help improve your body’s response to illness and reduce your susceptibility to conditions like the flu.
When you’re not feeling up to cooking or eating a full meal, some quick and easy snack options include soup, which is soothing and provides essential electrolytes; fruits that are packed with vitamins; and nuts and seeds that offer calories and healthy fats.
Why Am I Losing Weight But Eating More?
Losing weight, even while eating more, can be caused by different factors. First, the fact that you’re eating more doesn’t necessarily mean you’ll gain more weight. This is the case when you eat more healthy fruits, vegetables, and lean proteins that contain fewer calories.
Another factor to consider is your workout schedule or movement habits. If you engage in regular exercise and also take long walks or the stairs, you can raise your daily energy expenditure, contributing to weight loss.
If none of the above reasons apply, it’s important to consider the possibility of an underlying medical condition, such as a thyroid problem or an eating disorder. Consulting with a doctor is recommended in such cases.
When sick with a fever, your body burns more calories as it raises your basal metabolic rate (BMR) to increase your temperature and enhance your immune response.
However, when sick without a fever, you likely won’t burn many extra calories.
Weight loss during illness is often temporary and primarily due to water loss, but significant calorie deficits can lead to fat or muscle loss.
It’s generally recommended to eat a little extra when you have a cold to aid the body’s response to illness.
If you’re losing weight despite eating more, factors such as healthier food choices or increased physical activity may contribute, but underlying medical conditions should be considered. Consulting with a doctor is recommended in such cases.
Mayo Clinic: “Metabolism and Weight Loss: How You Burn Calories”
Huff post: “What To Eat When You’re Sick”
NorthShore University HealthSystem: “True or False: Feed a Cold, Starve a Fever?”