When you go keto, you know to load up on fats and kiss carbs goodbye—but what do you do about protein? Too much of the muscle-building macronutrient can cause trouble on keto. Here’s how to tell if you’re going overboard.

How Much Protein You Can Have On Keto

Despite the focus on keto being super low-carb and high-fat, it’s important to remember that the diet is also moderate-protein.

That means just about 20 percent of your daily calories, on average, should come from protein. That’s about a gram of protein per kilogram of body weight, or somewhere between 60 and 120 grams of protein a day, depending on your size, says Ginger Hultin, M.S., R.D., spokesperson for the Academy of Nutrition and Dietetics. (Since individual protein needs vary, Hultin recommends working with a dietitian to figure out your macros before starting keto.)

Why Protein Matters On Keto

The reason for keeping protein intake moderate on a keto diet: Too much can actually mess with your ability to burn fat.

“If you eat more protein than the body needs, your body can turn its amino acids (the building blocks of protein) into glucose (blood sugar),” says Hultin.

In this process, called gluconeogenesis, the body produces glucose using non-carb sources, explains integrative nutrition health coach Karissa Long, C.H.C. Why? Because glucose is easier for your body to access for fuel than fats, it opts to make and use glucose whenever possible—even if it has to use protein instead of carbs to do so.

Related: What A Day Of Healthy Keto Eating Looks Like

Thus, if you consume excess protein, your body will use those amino acids to produce glucose before starting to break down fat into ketones. The result: You get stuck in sugar-burning mode and can’t shift into ketosis.

Signs You’re Eating Too Much Protein

Not sure if too much protein is messing with your fat-burning abilities? Here are two big signs to look out for—and how to get your macros back on track.

1. Your Breath Smells Like Ammonia

While stanky breath that reminisces of nail polish remover is a normal side-effect on keto, breath that smells like ammonia is not.

“Interestingly enough, ammonia is produced by the body when it digests and breaks down protein,” Long explains. “When you ingest large amounts of protein, ammonia production can make your breath smell.”

So, if your breath smells like Windex, your protein intake may be high enough that it’s pulling you out of ketosis.

2. You Have Flu-Like Symptoms

When too much protein shifts your body out of ketosis, it essentially leaves you stuck in a metabolic limbo.

Like when you first start a keto diet, this state of transition can leave you with symptoms described as the ‘keto flu.’ Due to shifts in electrolyte levels and hydration that occur during this metabolic shift, you may experience “low energy, irritability, headache, muscle cramps and digestive troubles,” says Hultin.

Related: 4 Types Of Supplements Keto Dieters Should Consider

While keto flu symptoms typically clear up in about a week or so, as the body fully shifts into fat-burning ketosis, eating too much protein can bring them back over and over again as your body tries bounces between burning sugar and burning fat.

How To Get Your Protein Intake On Track

If you’re unsure whether your keto diet is actually too high in protein, you’ll first need to get a clearer picture of your intake. To do so, Long recommends tracking your food in an app for at least a few days. If you’re eating more than about 20 percent of your daily calories from protein, you’ll need to adjust your meals and snacks to tone it down.

Another surefire way to test whether your keto diet is actually achieving its purpose: Test your ketone levels. Using at-home strips, you can tune into the amount of ketones present in your urine, and make sure levels are in the true ketosis range. Many test strips—like Finaflex’s Ketone Test Strips—start off beige in color, and take on a pink or purple hue, depending on the amount of ketones detected. If you don’t fall into the optimal range, take a look at your protein intake and adjust as needed.

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