The strict carnivore diet (all-animal foods) — here focused on beef and beef liver — is an extreme form of ketogenic eating. Proponents claim benefits for weight loss, inflammation and strength, but scientific data are limited . Nutritionally, this diet typically provides ~70–75% of calories from fat and ~25–30% from protein . It is very low in carbohydrates (<5% of energy), essentially forcing ketosis . However, eliminating plants risks micronutrient gaps. Analyses show 100% carnivore plans meet or exceed needs for B-vitamins (B₂, B₃, B₆, B₁₂) and minerals like iron and zinc, but fall short in vitamin C, thiamin, magnesium, calcium, potassium and fiber . Liver (offal) can supply nutrients (iron, vitamin A, B₁₂, folate) often missing in muscle meat ; e.g. a 3-oz beef liver has ~17 g protein and is a “superfood” rich in iron and B-vitamins . However, liver is extremely high in pre-formed vitamin A, and daily intake can cause toxicity (vision/bone issues) .
Early reviews caution that carnivore diets are untested. Harvard Health experts warn of very high saturated fat raising LDL cholesterol, risking heart disease, and potential kidney stress from excess protein . Carnivore diets indeed spike cholesterol and triglycerides (e.g. one strongman’s bloodwork showed “very high” TGs and plaque buildup after 90 days) . Removing fiber and plant bioactives may harm gut microbiome and colon health . Critics note no peer-reviewed evidence that cutting plants yields special anti-inflammatory effects . Nevertheless, many anecdotal reports and a 2,000-person survey suggest carnivore dieters feel less pain and lose weight – though such self-reports are subject to bias and lack controls .
Key Nutritional/Health Points: Beef and liver supply abundant protein, iron, B-vitamins and vitamin A, supporting blood and muscle function . But strict carnivore diets lack fiber and vitamin C, risking scurvy and microbiome changes . High red meat intake is linked in studies to increased LDL cholesterol and cardiovascular risk . Registered dietitians caution that, despite weight loss and stable energy claims, the diet’s long-term safety is unproven and may require close medical supervision .
Effects on Body Composition and Performance
Muscle Hypertrophy and Strength
Muscle growth on a carnivore diet depends on training and protein intake, not the absence of carbs. Beef provides ample amino acids for muscle protein synthesis (e.g. ~60 g protein per 340 g steak) . Research on low-carb vs. high-carb diets in resistance-trained men shows equal or greater muscle and lean mass gains on very-low-carb (VLCKD) diets. In one 11-week trial, VLCKD trainees gained ~4.3 kg lean mass (versus 2.2 kg on a high-carb diet) and lost more fat . Strength improvements (bench/squat 1RM) were similar on both diets . Thus, with adequate calories and 1.6–2.0 g/kg protein, a beef-based diet can support hypertrophy. As one review noted, “if you can tax your muscles and eat enough protein/calories, carnivore is fair game” .
However, very high training volumes or multiple workouts per day may expose low-carb limits. A systematic review of training studies suggests that for workouts involving >10 sets per muscle group, some carbohydrate (≈1.0–1.2 g/kg/hr) around training may improve performance and recovery . Without carbs, longer high-intensity sessions (e.g. athletic games or two-a-day sessions) may suffer, as one soccer case study found: a female athlete on carnivore initially had higher game stress (TRIMP) than peers, but her performance normalized after adding moderate carbs pre- and post-game . In contrast, for typical bodybuilding sessions (≤10 sets muscle/group) research indicates similar muscle and strength gains can be achieved on low-carb as on higher-carb diets .
Key Points for Muscle/Strength: With sufficient protein intake and training stimulus, beef-and-liver diets can build muscle. Studies find low-carb athletes build lean mass as well as high-carb peers . Strength (1RM) gains tend to be comparable . Dietary fat-rich animal foods may support testosterone production: observational data link high saturated-fat intake to higher testosterone , and one resistance-training trial reported a significant T increase (≈118 ng/dL) on a very-high-fat diet (vs. a decrease on a carb diet) . In practice, most carnivores focusing on muscle ensure ≥2 g/kg protein and calorie balance, and some even use targeted “protein-only” or small carb refeeds around heavy sessions if performance lags.
Fat Loss and Body Composition
Carnivore diets almost always induce weight/fat loss, mainly via calorie reduction and metabolic shifts. Eliminating carb-rich foods typically lowers total intake, and ketosis increases fat burning. For example, the strongman Eddie Hall lost ~9 kg (20 lb) and 7.2% body fat in 13 weeks on carnivore, while slightly increasing lean mass . His coaches attributed this mainly to the large drop in carb (and alcohol) calories, and the attendant loss of water weight from glycogen depletion. Similarly, users often report stable appetite and high satiety from fatty meat, easing adherence and caloric deficits .
Intermittent fasting (IF) further amplifies fat loss. Time-restricted eating (TRE) regimens (e.g. 16:8) enhance daily ketosis and may spur autophagy and hormonal swings (GH increase) beneficial for fat burning. A 12-month TRE study (with resistance training) showed significant reductions in weight and fat mass . A 2024 systematic review concluded that IF “does not have a negative impact on sports performance” and generally improves body composition: it consistently reduced body fat without compromising strength or aerobic/anaerobic capacity . In practice, most carnivore-IF practitioners cycle two large meat-based meals and fast ~16 hours, achieving leaner physiques while maintaining muscle.
Key Points for Fat Loss: Both carnivore and IF promote fat loss. Clinical trials of IF report significant reductions in fat mass (and related inflammation) when coupled with strength training . Anecdotally, carnivore practitioners report rapid fat reduction along with mental clarity (likely via stable blood sugar) . Of course, any very-low-carb plan causes initial water loss; sustained fat loss requires maintaining a calorie deficit. In summary, for an intermediate lifter: a 100% beef/liver diet plus 16:8 fasting can robustly cut fat while sparing lean tissue .
Energy Levels and Exercise Performance
Many carnivore adherents report stable, high energy with few “crashes” . Physiologically, with the body fat-adapted, muscles and brain run on ketones and fat rather than glucose, which can stabilize energy levels. One bodybuilder on a strict steak-and-eggs regimen noted “zero issues with energy” during and between training sessions . Some low-carb athletes even train fasted without fatigue (though performance may improve once fully keto-adapted). However, without carbs one may notice reduced power in very short, maximal efforts (e.g. sprint or Wingate tests) unless well adapted. Overall, moderate-intensity and strength workouts remain effective on carnivore; extreme endurance or HIIT may require careful management or periodic carb intake (as one case study showed) .
Hormonal Effects (Testosterone, Cortisol, Insulin)
Carnivore diets are high in cholesterol and saturated fat, key substrates for sex-steroid synthesis. Indeed, some research suggests higher saturated-fat diets correlate with higher testosterone . In the resistance training study above, the all-meat (5% carb) group had a ~5% rise in total testosterone, whereas the high-carb group saw a decline . In contrast, intermittent fasting tends to lower testosterone in lean men. A 2022 review found IF reduced testosterone in physically active young males (though muscle mass/strength remained unaffected) . Likewise, a 12-month TRE study saw improved insulin and inflammation markers but reduced T . Rupa Health (2024) notes that IF can reduce testosterone by ~10–15% in men , which could impact libido and metabolic health. Thus, combining IF with carnivore may blunt some T production, especially if the person is lean and over-fasting.
However, IF also brings hormonal benefits: lower insulin, higher growth hormone and better insulin sensitivity are well-documented . These can indirectly support muscle and fat metabolism. Cortisol spikes during fasting may occur, but usually normalize once adapted. In practice, weightlifting itself robustly boosts testosterone, so a well-fed anabolic window post-workout (within the eating window) can mitigate IF’s impact. In short, carnivore+IF may slightly lower baseline T, but maintain it if bodyfat is healthy and training is intense.
Inflammation and Recovery
Removing refined carbs and processed foods (and often dairy/gluten) can reduce inflammatory markers and symptoms in some people. Carnivore diets eliminate dietary antigens (lectins, phytates) that some hypothesize to irritate the gut. Many users report relief from arthritis or autoimmune symptoms. Yet, formal evidence is lacking: experts note no solid trials showing carnivore diet uniquely reduces inflammation more than other diets . Any inflammation drop likely stems from weight loss, ketones (which have mild anti-inflammatory effects), and elimination of common allergens. Recovery from strength training on carnivore appears adequate as long as protein is ample. Ensuring minerals (electrolytes, vitamin C from liver, omega-3 from fatty cuts or supplements) helps mitigate potential inflammation or oxidative stress.
Key Hormonal/Inflammatory Takeaways: Carnivore diets supply cholesterol to support hormone production, and studies show high-fat, low-carb diets can raise testosterone compared to high-carb diets . However, prolonged fasting windows may lower testosterone in fit men . Overall, expect stable energy and recovery with this regimen; trainees often feel reduced joint pain and rapid recovery once adapted, though they must watch iron/heavy-metals and antioxidant status .
Intermittent Fasting: Benefits and Risks
Combining carnivore with IF (e.g. 16:8 daily, fasting ~16h, eating in 8h) can intensify ketosis and simplify eating. Benefits: IF typically accelerates fat loss (by extending fasting-state fat oxidation) and promotes autophagy/mitochondrial health. It often improves insulin sensitivity and lowers blood glucose, aiding health . In athletes, TRE protocols maintain performance while helping lean mass retention . Anecdotally, fasted training can boost growth hormone and fat burning; many carnivore-IF users report clear morning energy and improved focus (though data are sparse). A 2024 review found that IF (including 16:8) “does not have a negative impact on sports performance” and may slightly improve body composition .
Risks and Considerations: Extended fasting requires discipline and can strain hormones if overdone. As noted, IF often lowers testosterone in lean, active men , though weight loss may counteract this in overweight individuals. Fasted training may feel harder initially; some report reduced power output on high-volume sessions until keto-adapted. Post-workout nutrition is critical: even on carnivore, it is advisable to consume ample protein (≥0.3 g/kg) soon after lifting to maximize muscle protein synthesis . Some experts suggest a small carbohydrate (e.g. from fruit or honey) around heavy workouts to spike insulin, glycogen and recovery, though purist carnivores skip this. Also, fasting may cause headaches or fatigue in beginners, and strict IF can be socially challenging. Chronic IF could theoretically impact cortisol; adequate sleep and stress management are vital.
In summary, IF with carnivore can support athletic recovery by optimizing body composition and metabolic health, but requires careful planning: ensure hydration, replenish electrolytes, and adjust fasting duration if energy or hormones suffer. Most research indicates no loss of strength or lean mass when IF is well-managed .
Practitioner and Athlete Experiences
Several high-profile figures have experimented with or promoted meat-only regimens:
- Eddie Hall (World’s Strongest Man): In a 90-day “steak-only” trial, Hall dropped ~9 kg weight and 7.2% body fat while adding ~0.5 kg lean mass . He reported feeling “the strongest I’ve been in 4 years” (lifting records improved) . However, blood tests showed very high triglycerides, LDL cholesterol, and iron markers (from massive red meat intake) . His team advised adding vitamin C, omega-3s and plant foods afterward.
- “Liver King” (Brian Johnson): An influencer who famously ate 12 lbs of raw meat/organs daily (beef liver central) claiming ancestral health. He touted raw liver’s nutrient power for muscle and energy . However, he later admitted heavy steroid use and, in 2025, publicly distanced himself from the diet’s supposed infallibility . Medical experts cite his story as a caution: such extreme carnivory without steroids is unproven.
- Joe Rogan (Podcaster): Though not an elite athlete, Rogan’s public experiments influence many. He reported a 30-day all-meat “carnivore” cut resulted in 12 lb weight loss, increased energy and reduced joint pain . However, he also suffered severe diarrhea and eventually reintroduced some plants. Nutritionists (cited by Insider) warn of nutritional deficits (fiber, vitamins) on zero-carb diets .
- Historical and Other Anecdotes: Bodybuilding legend Vince Gironda in the 1960s endorsed a “meat and eggs” diet for contest prep, roughly analogous to carnivore+IF . Modern blogs and forums feature many lifters claiming stable gains and cuts from carnivore. For example, one athlete on a steak-and-eggs plan reported “no issues with energy… very stable… even after high-carb refeeds” (he occasionally added a weekly refeed pasta meal, but still felt strong). Such accounts are encouraging but anecdotal.
Key Insights: Individual results vary. Some lifters and biohackers find that a beef-centric carnivore diet (with fasting) boosts mental clarity and gut comfort, as all fiber/antinutrients are eliminated. Strength sports enthusiasts report maintained or even increased power if calorie-protein intake is high . However, these “N=1” successes coexist with warnings: any such regimen should be short-term (cut phases) or carefully monitored, given risks to cholesterol, micronutrients and hormonal balance.
Sample Meal Plan and Workout Split
Below is a hypothetical weekly plan for an intermediate male (≈80 kg) combining 16:8 IF with 100% beef/liver diet. Adjust portions for individual caloric needs. All meals include only beef or beef products; water and electrolytes can be consumed outside meals. Organ meat (liver) is included ~2–3 times/week for nutrients. This plan assumes two meals (e.g. at 1 pm and 8 pm):
| Day | 1st Meal (after fast) | 2nd Meal (evening) |
| Mon (Pull/Back) | 400 g ribeye steak (≈80 g protein, 80 g fat) | 300 g ground beef (≈60 g protein, 30 g fat) + 100 g beef liver (≈20 g protein, 3 g fat) |
| Tue (Legs) | 500 g grass-fed hamburger patties (90 g prot, 45 g fat) | 300 g flank steak (50 g prot, 25 g fat) + 100 g beef liver (20 g prot, 3 g fat) |
| Wed (Rest) | 400 g sirloin (60 g prot, 40 g fat) + 100 g beef liver (20 g, 3 g) | 500 g beef short ribs (60 g prot, 70 g fat) |
| Thu (Push/Chest) | 400 g ribeye (60 g prot, 60 g fat) | 300 g ground beef (60 g prot, 30 g fat) + 100 g beef liver (20 g prot, 3 g fat) |
| Fri (Shoulders/Arms) | 500 g flank steak (85 g prot, 50 g fat) | 300 g beef chuck (60 g prot, 35 g fat) + 100 g beef liver (20 g prot, 3 g fat) |
| Sat (Rest) | 400 g ribeye (60 g prot, 60 g fat) | 500 g ground beef (90 g prot, 45 g fat) |
| Sun (Rest) | 300 g sirloin (45 g prot, 30 g fat) + 100 g beef liver (20 g, 3 g) | 400 g ribeye (60 g prot, 60 g fat) |
- Totals (approx): 180–200 g protein and 150–200 g fat per day, for ~2,500–3,000 kcal (70–75% fat) . This aligns with estimated needs (male ~2,660 kcal) on a carnivore diet .
- Notes: All fat from beef is included; extra tallow/butter can be added if calories are low. Beef liver provides iron and vitamin A (but should be limited to 200–300 g/week to avoid hypervitaminosis A ). Bone broth or salt can be used as “snacks” to ensure hydration/minerals.
For training, a 4–5 day split is effective. One example:
| Day | Workout Focus | Example Exercises (sets×reps) |
| Mon | Pull (Back/Biceps) | Deadlift 4×5; Pull‑ups/Rows 3×8; Face-pulls 3×12; Curls 3×10 |
| Tue | Push (Chest/Triceps) | Bench press 4×5; Overhead press 3×8; Dips 3×10; Triceps extension 3×10 |
| Wed | Legs/Abs | Squat 4×5; Romanian DL 3×8; Lunges 3×10; Plank/Crunches |
| Thu | Shoulders/Arms | Incline bench or push-ups 3×8; Lateral raises 3×12; Arm superset 3×10 |
| Fri | Full Body (Optional) | Light compound moves (e.g. Goblet squat, push-pull circuit) |
| Sat/Sun | Rest/Light Cardio | Walking, stretching or recovery work |
- Training Tips: Perform workouts late in the fast (just before meal) or during the eating window so post-workout protein can be consumed soon after training. Aim for ≥20–30 g protein in the first meal after lifting (e.g. 300–400 g steak provides this) . Keep workout volume moderate (3–4 exercises per session) to preserve strength on low-carb. Focus on heavy compounds for growth, and use bodyweight or machines as needed. Ensure adequate sleep and include refeeding or extra fats on heavy training days if energy dips.
References
All statements above are supported by current sources. Key findings are drawn from recent reviews and studies: e.g., a nutrient-analysis of carnivore meal plans , strength & carb research , IF studies , and case reports of athletes on carnivore . Clinical advice from authorities (Harvard Health) is also cited . This evidence shows that a 100%-beef (plus liver) carnivore diet with IF can support muscle gain and fat loss when correctly managed, but carries nutrient and metabolic risks that warrant caution and monitoring.