Feed a Cold, Starve A Fever? What to Eat (Or Not) When You’re Sick

Woman sits looking dejectedly at thermometer surrounded by crumpled tissues.Cold? Flu? Tummy troubles? I know that I don’t have time to be sick, and I’m sure you don’t either. Luckily I don’t get sick very often anymore, but back in my competitive athlete days, it felt like I was constantly battling one cold, cough, or sinus infection after another.  

Not to toot my own horn, but I chalk up my current good health to my Primal lifestyle. I know for sure that there is a marked before and after—before Primal, when I had a medicine cabinet full of OTC remedies, and after, when I rarely take a sick day. On those occasions when I do detect a tickle in my throat or the first signs of sour stomach, my first course of action is to double down on those aspects of my lifestyle that support a robust immune system, particularly nutrient-dense foods, sleep, and time in the sun.

The food piece is what we’re going to talk about today. Everybody has an opinion about what to eat, or not, when you’re under the weather. I’m not claiming that certain foods can cure the flu or prevent you from coming down with that cold even after your sick kid coughs in your face. But once you’re sick, the name of the game is supporting your immune system by providing it with beneficial nutrients and compounds that could aid it in fighting off the viruses or bacteria that are making you sick in the first place. Some foods will also provide welcome comfort, which is nothing to sneeze at, pun intended. 

(I should note that I’m talking today about recovering from short-term issues—common cold, flu, a bout of food poisoning, that sort of thing. Chronic illnesses are a whole other ballgame.)

But maybe you shouldn’t eat anything at all? You’re probably familiar with the old adage, “Feed a cold, starve a fever.” Are you unintentionally doing more harm than good by eating even supposedly “healing” foods? 

Let’s dive into it. 

Feed a Cold, Starve a Fever? Yes or No?

As usual, it’s complicated.

I’ve covered the issue of fasting with a cold or other illness in depth before, but the short answer is that fasting may be beneficial in the case of a bacterial infection like a sinus infection but probably isn’t beneficial when battling viral illnesses like the common cold or coronaviruses. 

Here’s where it gets complicated: bacterial and viral illnesses often go hand-in-hand. You get sick with a virus, your immune defenses become compromised, and a bacterial illness takes root. Thus, it’s not always clear what, exactly, ails you. 

Furthermore, both can cause fever as part of a desirable immune response. The idea behind starving a fever is that eating increases body temperature (true). If you’re already “too hot,” you don’t want to pile on. That makes sense on face value. However, fever (or rather, the underlying immune response it represents) is a calorie-intensive process. For every 1 degree Celsius increase in body temperature (1.8 degrees Fahrenheit), metabolic rate ramps up by an estimated 10 percent.1 Fasting when you have a fever, regardless of its origin, may make it harder for your body to continue to launch a robust immune response. That’s why the more common recommendation now is to feed a fever—to meet the increased need for energy and nutrients.  

What if you have no appetite when you’re sick?

Ah, another wrinkle to consider. Appetite loss is a common feature of many types of illness, and not just in humans. Animals across the species spectrum display the same anorexic (literally “without appetite”) response to being sick.

Scientists speculate that this is adaptive for a number of reasons.2 When a sick animal isn’t driven to go out and find food, it conserves the energy normally spent hunting or foraging. Instead, it can hunker down in its shelter, where it is also safe from predators it may not be able to evade in its current weakened state. 

Fasting has other benefits as well. Yes, you aren’t taking in nutrients and calories that your immune system could use to fight foreign invaders, but you’re also depriving those same invaders of nutrients that they could use to reproduce and make you sicker.3 Fasting can also put you in a state of ketosis. Ketones, particularly beta-hydroxybutyrate, have anti-inflammatory and anti-oxidative effects that can protect against acute illness via a variety of complex metabolic pathways.4

All things considered, I believe that listening to your body is usually the best course of action. If you don’t have any appetite when you’re sick, there’s probably no problem with—and potentially some benefit to—fasting or just eating small meals. Staying hydrated is very important, though. Make sure you stay on top of fluid intake and consider adding electrolytes (especially if you’re feverish or have diarrhea). If appetite loss lasts longer than a couple days, or if you feel yourself becoming weaker or truly unable to eat, contact your doctor. 

4 Foods to Eat When You’re Sick

Ok, but what if you do have an appetite? What if you want to support your immune system with foods that could potentially help it knock out the illness faster? What then? 

Here’s where I’d start.

1. Bone broth and soups

Bone broth is a rockstar when it comes to helping you feel better. Besides the comfort factor of eating a bowl of steaming chicken soup when you’re not feeling well, research affirms that bone broth can help the body recover from upper respiratory infections.5 Hot liquids also keep mucus flowing which, while gross, allows the body to purge infectious agents. Chicken soup seems to be even more effective in this regard than plain hot water.6 (I expect any type of bone broth would have the same effect.)

The glycine in bone broth is also a natural sleep aid, and we all know that good sleep is key to recuperating from illness or injury. 

How to get it: 

I’m partial to homemade bone broth (here are recipes for chicken broth and turkey broth in the Instant Pot, for example), but store-bought is fine too. Sip it straight or make a bone broth latte

Soups that contain meat and vegetables are great ways to get extra nutrients in. I’m especially partial to garlicky soup. There is some evidence, though not always from very high-quality studies, that antibacterial and antiviral compounds in garlic can be useful in combatting everything from the common cold and flu to dengue virus.7 8 (I hope it goes without saying that you shouldn’t just chomp down on a few cloves of garlic if you have dengue fever. Get to an emergency room!) 

Long-time readers may recall me mentioning that when I feel a cold coming on, my immediate response is to simmer a whole head of crushed garlic in a pot of broth with cayenne pepper. This Garlic Soup with Mushrooms recipe will have the same effect but with even tastier results. 

Or if you’re feeling hardcore, go ahead and eat a clove or two raw. Some people swear by raw garlic for relieving a sore throat. 

2. Turmeric tea, or golden milk

Golden milk is the perfect mix of ingredients, each of which is immune-supporting in its own right:

  • Turmeric, which contains the anti-inflammatory and anti-oxidative compound curcumin9
  • Ginger, which may be especially beneficial if you’re experiencing nausea or upset stomach
  • Honey, which research has proven effective for relieving sore throat10 and cough11 (the latter even better than pharmaceuticals in some cases)


A warm mug is just the ticket when you’re not feeling so hot. This golden milk recipe calls for coconut or almond milk, but if you can do cow milk, they whey and lactoferrin may provide an extra boost, helping you feel better if you’re suffering from a cold.12 

If you’re feeling more savory than sweet and want to harness the power of bone broth while you’re at it, try my Ginger Turmeric Chicken Soup instead. There’s a reason it’s one of the most popular recipes on the blog. 

3. Fermented foods

You already know that fermented foods are important sources of probiotics that help nurture a healthy gut microbiome. I recommend increasing your intake of fermented foods any time you have GI issues or immediately if you must take an antibiotic

But fermented foods aren’t just for gut health. In one study, researchers asked college students to supplement with probiotics or a placebo for 12 weeks and tracked the incidence of upper respiratory infections during that time.13 Although both groups were equally likely to get sick, the probiotics group had less severe symptoms, missed fewer days of school, and recovered two days faster on average. A meta-analysis of 20 randomized controlled trials found similar results in children and adults with respiratory illnesses.14 

How to get them: 

Any fermented foods will do, but a bowl of sauerkraut or a giant deli pickle might not sound great when you’re sick. Some spicy kimchi or sambal oelek would do wonders for clearing stuffed sinuses, though! 

Yogurt or kefir are probably your best bets. The studies mentioned above used various probiotic strains, but Lactobacillus rhamnosus was a common one that you can probably find in yogurt from your grocery store.

4. Smoothies

I’m not much of a smoothie guy generally, but I mention them here for a few reasons. They may be more tolerable than a full meal if you have a stomach ache or sore throat. You can incorporate many of the beneficial items above (yogurt, whey, turmeric, etc.) into a smoothie. And smoothies usually contain other ingredients that support the immune system in their own right, such as berries for polyphenols or greens for magnesium and other vitamins.


Now I’m sure some of you are wondering if smoothies are a good idea since sugar suppresses the immune system. That’s true, but I’m less worried about whole fruit in a smoothie than the boluses of sugar often administered in studies, especially if you aren’t eating all that much period because you’re sick. And smoothies don’t have to be loaded with sugar. Check out these smoothie bowls that feature a variety of healthful ingredients. Or try a keto-friendly avocado smoothie

What Should You Eat with an Upset Stomach?

I bring this up because it’s a question I get fairly regularly. The standard advice in this situation is to adhere to a BRAT diet. That’s bananas, rice, applesauce, and toast. Not very Primal sounding.

But let’s stop and examine this for a second. The idea behind the BRAT diet is that these foods are fairly well tolerated when you have nausea, vomiting, or other GI issues. They’re bland and easily digested. 

And on the scope of food options, they’re not all that bad, Primally speaking. Of all the grains, rice is arguably the most innocuous. I don’t encourage people to eat rice, but it’s in that gray area of “not the worst, especially if you’re insulin sensitive and want to add some carbs to your diet.” Bananas are the same. I even declared bananas an underrated superfood once, especially when they are on the greener side. Applesauce is just apples with some of the mastication done for you. You could even do toast in a Primal-friendlier way by choosing one of the many gluten-free (even grain-free) options now widely available. 

Am I going to promote the BRAT diet? Not exactly. If you can tolerate some scrambled eggs or a blended soup, go for that. But if you’re sick and hungry, and a banana or some applesauce is all you can tolerate, I don’t want you wondering if the specter of Sisson is looking over your shoulder and tut-tutting.  

And don’t forget that ginger and peppermint are both great for upset stomach. Try some ginger or peppermint tea, or take a few whiffs of peppermint essential oil before trying to eat something. 

Prevention Is the Best Medicine

In terms of dietary components (vitamins, minerals, polyphenols) that support the immune system, it’s better to keep yourself adequately supplied all the time than to try to load up via foods or supplements while you’re already sick. High-dose vitamin C or zinc might help knock out a cold, for example, but a better strategy is to play offense instead of defense by eating nutrient-dense Primal foods consistently. 

I’m sure some of you have foods you swear by when you’re sick. Maybe it’s a special concoction a parent or grandparent used to whip up—your family’s secret, fail-proof recipe. Share your best  illness-combatting tactics in the comments. 

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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