35 Days on the Carnivore Diet: Performance, Energy, and Health Changes

By Jackson Mann, MTI Intern

I spent 35 days on the carnivore diet, a nutritional approach that eliminated all plant-based foods in favor of animal products. Going into it, I didn’t have any specific goals or expected outcomes—I was simply curious to see if I could stick to such a highly restrictive regimen. In the past, I had tried low-carb diets and experienced general improvements in health. However, those still allowed enough carbohydrates to support my active lifestyle—or at least it felt that way. With the carnivore diet, I wanted to see how it would impact my body in terms of performance and overall well-being. What I experienced was a mix of challenges, subtle benefits, and some surprising insights into how I functioned without carbs.

The first week and a half was rough. My digestion struggled to adapt, and I had constant cravings for sweets and carbs. Transitioning from a relatively balanced diet to one built entirely around meat and animal fats shocked my system. I felt low energy, needed more rest than usual, and had to fight off urges to break the diet—especially when surrounded by tempting non-carnivore options. Socially, eating out became a challenge. Ordering plain meat dishes led
 to a few awkward conversations with waitstaff and more than a few confused looks.

By the second week, however, things began to shift. My digestion leveled out completely, and I stopped craving sugary or starchy foods. One of the most noticeable changes was how rarely I felt hungry. Meal frequency naturally dropped, and my energy began to stabilize. While I didn’t notice any major difference in performance during my weekly six-mile rucks, I also didn’t feel like I lost much—if anything—in terms of endurance. I even continued to make strength gains during this period, hitting a new 1RM back squat and increasing my reps during a 10-minute sandbag get-up session.

In terms of weight, I lost around 3–5 pounds, though that fluctuated depending on the time of day I weighed myself. Some days, I was down as much as six or seven pounds from my starting weight. Sleep also changed noticeably. I needed more rest during the first two weeks, but toward the end, I felt like I needed less sleep overall and still woke up feeling recovered.

The hardest part of the carnivore diet wasn’t the food itself—it was the lack of flexibility. I missed the variety, the spontaneity of grabbing something convenient, or sharing a meal that wasn’t centered around steak, eggs, or burger patties. That said, I finished the 35 days feeling physically fine, mentally clearer, and with a better understanding of how my body handled different types of fuel. Unexpectedly, my seasonal allergies disappeared, and my skin cleared
up—two benefits I hadn’t anticipated.

Overall, the diet was a cool experience, and I know I can return to it in the future if needed. However, I’m glad to be eating a variety of foods again and no longer have to hyper focus on what I can and can’t eat.

Jackson, age 20, is a ROTC Student in California and just completed a 2-month internship at the MTI lab in Ogden, UT.