Why you lose appetite when sick

For the short-term illnesses that most of us encounter, diminished food intake has no prolonged effect.   It is not medically out of place or abnormal when a person gets sick, especially from an infectious agent like a bacterium, the body mounts a vigorous inflammatory response, said Dr. Clifford Saper, chief of neurology at Beth Israel Deaconess Medical Center. Among other things, the immune system pumps out hormones that end up in the brain, triggering fever, changes in the sleep-wake cycle (that's why you get so sleepy when you get sick), and appetite.


You loss appetite to reduce the growth of bacteria and viruses

Loss of appetite may also discourage viruses from growing more. Eating less “may decrease certain substances that viruses ‘feed’ on,” says Hensrud. Same goes for bacteria, which won’t find as much glucose and iron in the blood to feed on if you’re eating less. “This complex response is adaptive short term and can promote recovery and healing,” he says.

But that doesn’t mean you shouldn’t eat. Actively trying to starve out sickness and thereby depriving your body of enough calories could actually hinder the healing process, considering your body needs considerable energy stores to send your immune system into high alert. 

Losing your appetite during a bacterial infection is actually a good thing, Saper said. Bacteria live on a type of sugar called glucose. When a person gets sick and stops eating, there is less glucose around, which means bacteria essentially starve. The person, luckily, does not, because humans are well-adapted to use an alternate fuel, fat, to keep metabolism going.

Losing your appetite doesn't help fight viral infections but discourage its growth. Losing your appetite during a bacterial infection is actually a good thing, Saper said. Bacteria live on a type of sugar called glucose. When a person gets sick and stops eating, there is less glucose around, which means bacteria essentially starve. The person, luckily, does not, because humans are well-adapted to use an alternate fuel, fat, to keep metabolism going.
Losing your appetite doesn't help fight viral infections, because viruses don't live off glucose in the same way as bacteria., because viruses don't live off glucose in the same way as bacteria.

Brain changes during sickness

When you become ill, your brain chemistry changes as production of chemicals called cytokines increases. These chemicals can drive down your appetite, which will help you to conserve energy for fighting off short-term illnesses like the flu. Since your body requires lots of energy to digest food, loosing your appetite gives your body the ability to dedicate more energy and resources to fighting off the virus.

Sinus congestion during  cold or flu
Another side effect of the flu or a common cold is sinus congestion, which can diminish your sense of smell. Since smell and taste are so closely linked, you might simply want to eat less because you won’t be able to taste anything!

Foods to fight your illness
When you do muster up an appetite during your illness, you should never resist eating to try and “starve out” a fever. Reach for foods that are easy to digest like soup or dry whole-wheat toast, and avoid eating any junk food that could actually fuel your illness. If you really don’t want to eat, you might enjoy sipping on some ginger tea or clear broth to keep your stomach calm. The most important thing to remember when you’re sick is that your body may respond differently to illnesses, so you should not neglect your needs as your appetite changes. Here is the list of foods to eat during illness.

 PROTEIN-RICH FOODS
Dairy products such as yogurt, cottage cheese, and ice cream are protein-rich food choices that may be tolerable to individuals with appetite loss due to their light flavor and soft, easy-to-swallow texture. In addition, mixing ice cream or milk with a protein powder or instant breakfast drink mix can provide additional nutrients to ensure someone who has appetite loss gets the most nutrition from the small amount of food they may be consuming.

BLAND FOODS
Bland foods such as saltine crackers, plain cooked rice, plain pasta, mashed potatoes, or plain bread or toast, may be tolerable to individuals who have appetite loss as a result of illness, according to the Cleveland Clinic. Foods that are spicy, greasy, or high in fat or sugar may produce further nausea or vomiting and should be avoided during times of illness until the individual's appetite has returned to normal.

SUFFICIENT FLUIDS
According to the Cleveland Clinic, those who experience appetite loss with associated nausea or vomiting should be sure to drink sufficient fluids to prevent dehydration. Clear or ice cold drinks such as ginger ale or water, and drinking slowly will aid those with appetite loss in staying hydrated. Other ways for those with appetite loss to stay hydrated include eating fruit ice pops, gelatin, drinking iced tea or coffee, or eating ice chips.


COLD FOODS
Cold or room temperatures foods, according to the Mayo Clinic.com, may be more palatable to those individuals with appetite loss due to nausea since such foods produce a less potent smell than foods at a high temperature. Foods such as cold sandwiches, pasta or chicken salad, or chilled soups may be palatable for those with nausea or vomiting.

PORTION
Small, frequent meals every 2 to 3 hours may also help individuals with appetite loss for any reason to get the calories they need without overwhelming their digestive system. The Olin Health Center at Michigan State University adds that individuals with diabetes experiencing appetite loss should try to consume 15 g of carbohydrate every hour or 50 g of carbohydrate every 3 hours, along with their medication, in order to keep their blood glucose levels stable and prevent further illness.

 OTHERS INCLUDE
Hot Tea
Warm liquids can soothe a sore throat and alleviate congestion, so drinks like freshly brewed green tea—which is rich in infection-fighting antioxidants and supports the immune system—are ideal for staying hydrated while helping out that stuffy nose. If you don’t like tea, hot water with lemon should also do the trick.

Citrus Fruits
It’s a myth that vitamin C can cure the common cold, and there isn't much scientific evidence behind the theory that it can reduce the length or severity of your symptoms. But while citrus fruits might not be a cure-all, the soft white layer of skin found on oranges, lemons, grapefruits, and limes does contain flavonoids, which can help boost the immune system and speed up recovery.


Spicy Foods
Spicy foods can make your nose run and your eyes water, but they're also effective natural decongestants. Eat chili peppers, wasabi, or horseradish to help relieve the symptoms of congestion.

Foods That Settle Your Stomach
When it comes to stomach issues (which can accompany the flu), staying hydrated and eating bland things that are easy to digest are the quickest route to a speedy recovery. Here are a few of your best bets:

Crackers and Toast
Plain, unsalted, or lightly salted crackers and toast are easy on the stomach. These high-starch foods won't aggravate any nausea you may have and can help stabilize digestion (which is especially helpful after vomiting).

Bananas
Bananas are rich in potassium, which is often depleted during bouts of sweating, vomiting, or diarrhea. They're easier to digest (A+ for bland foods!), may help lower body temperature, and can help replenish lost electrolytes.

Ginger
Research has shown that ginger is incredibly effective at preventing and soothing nausea and other gastric ailments such as constipation, bloating, and vomiting. Drinking ginger tea or flat ginger ale (to avoid disrupting the stomach with carbonation) can help keep you hydrated while also soothing tummy troubles.