Macros On a Carnivore Diet

September 15, 2023

Original Publish Date: 1/14/23

There are four calories in one gram of protein and four calories in one gram of carbs. There are nine calories in one gram of fat, so gram for gram, a meal with more fat has more calories. And while calories in calories out (CICO) don’t always hold true for weight gain or loss, calories still matter.

My resting metabolic rate may be able to burn 1200 calories in a day, and a 60-year-old woman may only be able to burn 1000 calories in a day. This is one example of how CICO is not the same or does it hold true for everyone. But once I figure out my hormone health and metabolic function, CICO can make sense. Both of us cutting calories to 600 a day, while it won’t be good for longevity, it will allow for weight loss. Eventually, the CICO or severe calorie restriction will cause the body to shift to conservation mode and reduce metabolic functions (e.g., thyroid and hormone imbalances). CICO will no longer work to lose or maintain body mass.

This is the issue with protein-sparing modified fasts and mainly eating lean meat. You are eating sufficient protein but undereating calories. Long term, it’s not ideal for optimal health or longevity, (and also why many old advocates turned to carbs).

It’s likely what happened when many carnivore diet advocates pushed for lean days (ahem, we should hold them responsible). Fast forward nearly a year, and these same people are now advocating for high fat. Some have shifted to the inclusion of whole-food carbs.

Since fat has more calories per gram, the high-fat recommendations are now pushing protein low to ensure calories remain low. This is a mistake with protein needs. Below is the Recommended Dietary Allowance set to ensure we are not deficient in protein, which is 0.8 grams/1kg of body weight (0.4 grams/1lb of body weight). It is not ideal for any person and it is undoubtedly insufficient for carnivores.

Yet there are those on carnivore diets eating only about 50 to 60 grams of protein daily with 80% fat. 50 grams of protein within meat and 80% fat in terms of total calories is only 1070 calories (50 grams of protein and 95 grams of fat). As you can see below, 50-60 grams is close to the inadequate RDA protein levels. This is not ideal.

You risk hormone and thyroid issues on a carnivore diet if you don’t eat sufficient protein and also undereat calories. You also cannot stick to lean protein or grass-fed beef and be able to eat enough calories. (It’s likely why advocates add honey and fruit, and then the rest of the population starts adding donuts.)

If you do any of these “hacks” long term, you will likely have hormone and thyroid issues.

So what is the right amount to eat?

I interviewed Dr. Donald Layman again, and he reiterated the importance of protein being a required daily amount, whereas carbs and fat can be used as energy levers. I am a fan of 75% fat in terms of total calories on a carnivore diet. I’ve seen many of my clients heal in that range. Some people need 80% fat in terms of total calories, but we should not reduce the protein levels below 0.8 g per 1 lb. of ideal body weight long term. We risk losing muscle.

Dr. Layman mentioned that after the age of 40, once you lose muscle mass, it’s really difficult to regain. In one study, he noted that significant muscle loss was seen with excess fasting or bed rest. Young people lost one kg in a week, whereas adults lost an average of 12 kg in one week. (Source)

Some think that keto is muscle-sparing as the body relies on less glucose converting to glucose, thus sparing protein breakdown (Source). There are also thoughts that less nitrogen occurs on a ketogenic diet, causing the body to break down less protein. (Source) Some advocates believe ketones are anti-catabolic (they don’t break down muscle) but further research is required.

If 50% of falls at age 65 cause people to never walk again and 33% of the falls end up in death, I’m not willing to bet those ketones will save my lean body mass (or my fall).

TLDR: If you are eating 80% fat (and mostly butter) with limited protein (and calories), don’t blame the carnivore diet for (future) thyroid and hormone imbalances and loss of muscle mass long term.

If you are eating sufficient protein and insufficient fat (and total calories), don’t blame the carnivore diet for future poor thyroid and hormone function.

Just because you no longer feel the insulin-blood-sugar-roller-coaster, and rarely feel hangry, it doesn’t mean to start restricting. (Eat only when you’re hungry DOES NOT apply here). Don’t let vanity ruin your health. No one wishes they were thinner when they’re dying.