Are Carnivores Really “Fixing” Problems With Carbs – Or With Calories?

Disclaimer: This blog post does not intend to be dogmatic. Individuals are free to consume carbohydrates, and I respect their dietary choices. This post is not intended to criticize anyone’s dietary decisions. It is simply an observation that I wanted to share, and I welcome criticism and feedback.

Lately a lot of long‑term carnivores are announcing that they’ve added carbs back and suddenly everything is better: workouts, metabolism, thyroid, even stalled weight loss. You see it all over X and YouTube. The question is whether carbs are uniquely solving those problems, or whether people are just finally eating enough total energy after years of running on fumes.[1][2]

My working hypothesis: many carnivores quietly drift into chronic undereating because meat is so satiating, and most of the issues they later “fix” with carbs are really classic consequences of low energy availability.[2][3]

Point 1: Chronic Undereating Tanks Metabolism

When you go carnivore, appetite often crashes in a good way at first: less snacking, fewer cravings, easy fat loss. But that same satiety makes it surprisingly easy to eat too little for months or years.[4]

Extended calorie restriction is well known to:

  • Reduce resting metabolic rate as the body downshifts to conserve energy.[3]
  • Lower thyroid hormone output (T3 and T4), increase reverse T3, and create a state that looks a lot like hypothyroidism: low energy, cold intolerance, brain fog, stubborn weight.[2][3]
  • Disrupt leptin and ghrelin, which further confuses hunger signals and keeps you stuck in “low burn” mode.[2]

In other words, what many carnivores call “starvation mode” is basically textbook adaptation to chronic low energy intake, regardless of whether calories came from ribeyes or rice.[3][2]

Point 2: Low Energy, Not “Keto Adaptation,” Is Killing Workouts

Another big pattern: people say their training falls apart on strict carnivore, then magically improves when they add carbs. It is easy to blame low carb itself, but energy availability matters just as much as fuel type.[5]

Some key points:

  • In controlled studies, when total calories and protein are matched, low‑carb or ketogenic diets can maintain strength and muscle performance reasonably well after adaptation.[6][1]
  • Poor workouts, no “gas in the tank,” and worsening performance are classic signs that total intake is too low to support both daily living and training stress, not just that carbs are missing.[5][6]

If you are chronically under‑eating on carnivore, your body will prioritize basic survival over setting PRs. Once you raise calories—whether from more steak and fat or from adding carbs—performance usually perks up because you finally have enough energy to push hard and recover.[1][6][5]

Point 3: Gluconeogenesis Is a Feature, Not a Bug (When Fed Enough)

Carnivore critics often argue that gluconeogenesis (GNG) is “stressful” and proof that the body really wants carbs. There is a kernel of truth here: trying to make glucose in a deep calorie deficit is not fun. But the problem is the deficit, not the pathway.[4]

Research and basic physiology show:

  • On a well‑formulated low‑carb or ketogenic diet with adequate calories and protein, the body reliably produces enough glucose from amino acids and glycerol to cover essential needs (red blood cells, parts of the brain, etc.).[6][4]
  • Studies of ketogenic diets with sufficient energy intake report preserved lean mass and functional strength, which implies that GNG is not automatically “over‑stressing” the system when fuel is adequate.[1][6]

So in a fed state, gluconeogenesis is a normal, background process that ticks along to keep blood glucose stable. The stress shows up when you ask the body to maintain training, recover, and run daily life on chronically insufficient calories.[4][1]

From a practical standpoint, many low‑carb athletes perform fine using a combination of fat oxidation, ketones, and GNG‑derived glucose, as long as overall energy and protein needs are met.[5][6]

Point 4: Why Adding Carbs Feels Like Magic

So why do a lot of people feel dramatically better when they add carbs back?

A few likely reasons:

  • Total calories go up. Carbs are easy to overeat compared to steak, so people finally climb out of a long‑term deficit and feel human again.[7][2]
  • Glycogen refills. Carbs refill muscle glycogen quickly, which can make training feel easier and more explosive, especially for higher‑intensity work.[7][6]
  • Thyroid and hormones respond to energy, not macros alone. Raising energy availability tends to normalize thyroid output and other hormones that were suppressed by chronic restriction.[3][2]

From the outside, it looks like “carbs fixed my thyroid and metabolism.” Under the hood, the more accurate story is: “eating enough fixed my thyroid and metabolism.” Carbs are just the vehicle many people use to drive calories back up.[2][3]

The important implication for a carnivore is that you can likely get the same benefits by:

  • Increasing total food intake (more meat, more fat, or both).
  • Ensuring sufficient protein to support lean mass and function.
  • Avoiding long stretches of deep, unplanned restriction once you are already lean or highly active.[6][1][5]

Point 5: Protein–Fat Balance Matters (Avoiding “All Fat, No Muscle” Carnivore)

There is another trap on the opposite side: swinging into extremely high fat with relatively low protein. That can be a problem for body composition and thyroid health.[8][4]

Evidence and mechanisms to keep in mind:

  • Classic ketogenic macros are often around 70–80% of calories from fat, with only 10–20% from protein, which can push protein intake quite low for active people if calories are also modest.[4][6]
  • Low‑protein diets are associated with reduced thyroid function and symptoms like fatigue, poor recovery, and weight issues, especially when combined with overall calorie restriction.[8][2]

If dietary fat is very high and protein relatively low, the body may prioritize burning the fat on your plate instead of tapping stored body fat, while also skimping on the amino acids needed to maintain lean tissue and support gluconeogenesis.[8][6][4]

A more balanced approach many people do well with is roughly a 1:1 ratio of protein to fat by grams (adjusted up or down based on body size, goals, and training). That kind of balance:

  • Keeps protein high enough to support muscle, recovery, and healthy thyroid output.
  • Provides plenty of fat for energy and satiety without drowning protein in excess dietary fat.[1][6][8][4]

Bringing It All Together

Put simply, the carnivore‑to‑carbs stories do not prove that humans need carbs to have a healthy metabolism, strong workouts, or normal thyroid function. They do strongly suggest that humans need enough energy and protein, and that a very satiating carnivore pattern makes it easy to unintentionally under‑eat for a long time.[3][1][2]

If someone feels wrecked on carnivore and then feels amazing with some carbs back in, the first question should be: “Did your total calories (and protein) finally go up?” If the answer is yes, then the real lesson is about fixing chronic undereating, not about abandoning meat.[7][2]

Ultimately, if you are a carnivore and encounter the issues I outlined, you have options. You can incorporate more high-quality carbohydrates into your diet or increase your consumption of carnivore-friendly foods. Ultimately, it is your life and your choice.

Example Reference Definitions (you can replace these with your own)

Sources [1] Body Composition Changes After Very-Low-Calorie Ketogenic Diet ... https://academic.oup.com/jcem/article/102/2/488/2972058
[2] How Undereating Can Affect Your Thyroid | Paloma Health https://www.palomahealth.com/learn/undereating-thyroid
[3] Extended Low-Calorie Diets and Thyroid Dysfunction - AZ Dietitians https://azdietitians.com/blog/extended-low-calorie-diets-and-thyroid-dysfunction/
[4] Diet Review: Ketogenic Diet for Weight Loss - The Nutrition Source https://nutritionsource.hsph.harvard.edu/healthy-weight/diet-reviews/ketogenic-diet/
[5] The Carnivore Diet and Exercise Performance | Nutrition with Judy https://www.nutritionwithjudy.com/does-the-carnivore-diet-impact-exercise-performance
[6] Impact of the ketogenic diet on body fat, muscle mass, and exercise ... https://pmc.ncbi.nlm.nih.gov/articles/PMC10844723/
[7] Carnivore Diet Vs Carbs | Which Diet Is Better For You? https://www.garagestrength.com/blogs/news/carnivore-diet-vs-carbs-which-diet-is-better-for-you
[8] The effect of food groups and nutrients on thyroid hormone levels in ... https://www.sciencedirect.com/science/article/abs/pii/S0899900721002562

Rick CartwrightComment