The debate over whether a high-fat or high-carb diet is superior has been a contentious topic for years. Some experts advocate for the ketogenic lifestyle, which focuses on fat as the primary source of fuel, while others swear by the energy-boosting effects of carbohydrates.

But what happens when two identical twins—who share the same genetics—follow entirely different diets for 12 weeks? According to a fascinating experiment covered by Men’s Health, this unique study offers valuable insights into how each diet affects weight loss, muscle mass, and overall health.

The 12-Week Twin Diet Experiment

In this real-life test, identical twins Hugo and Ross Turner embarked on a diet experiment supervised by experts from King’s College London. This study provided a rare opportunity to understand how food choices impact individuals with nearly the same genetic makeup.

Here’s how the experiment was structured:

• Hugo followed a high-fat, low-carb die—commonly known as the ketogenic diet.
• Ross consumed a high-carb, low-fat diet, often classified as a traditional endurance athlete’s diet.
• Their calorie intake and protein levels were kept consistent to ensure fair comparison.
• Both engaged in similar workout routines and daily activities.

At the completion of 12 weeks, the results revealed surprising differences in their health, body composition, and energy levels.

The Results: High-Fat vs. High-Carb

1. Weight Loss and Muscle Mass

One of the most noticeable outcomes of the experiment was weight fluctuation.

– Hugo, on the high-fat diet, experienced significant weight loss in the first few weeks. However, much of it came from water weight due to reduced carbohydrate intake. Over time, his weight stabilized.
– Ross, on the high-carb diet, maintained a relatively steady weight throughout the experiment. Being fueled by carbohydrates, his body retained more glycogen and water, leading to less drastic fluctuations.

Muscle mass retention and strength performance were also key differences. Hugo reported feeling weaker during the early phases, while Ross, relying on carbohydrates, sustained his gym performance more effectively.

2. Energy Levels and Athletic Performance

A major takeaway from the twins’ experience was the impact of diet on energy levels.

– Hugo (high-fat diet) experienced the infamous “keto flu” in the beginning, which left him fatigued and sluggish. While his body eventually adapted to burning fat for fuel, he reported lower endurance levels during high-intensity exercise.
– Ross (high-carb diet) felt energized throughout, particularly for cardio-related workouts. His availability of quick-burning energy from carbohydrates provided sustained performance.

This suggests that while a high-fat diet can work over time, the energy demand for high-performance athletes might be better met with a high-carb approach.

3. Mental and Cognitive Function

How a diet affects brain function is just as important as its physical effects.

– Hugo (on keto) initially suffered from brain fog but later reported mental clarity once fully adapted to ketosis.
– Ross (on high-carb) described stable cognitive performance throughout without any adjustment phase.

This aligns with existing research suggesting that keto may enhance brain function for some, but the transition period can be challenging.

4. Mood and Cravings

Cravings and mood swings are common concerns when switching diets.

– Hugo mentioned reduced hunger levels as fats tend to be more satiating. However, he missed the convenience and variety of carb-based foods.
– Ross, meanwhile, had fewer restrictions, making meal planning easier. However, he occasionally experienced hunger spikes between meals, likely due to fluctuating blood sugar levels.

What Can We Learn from This Experiment?

While neither diet proved universally superior, several key takeaways emerged from this twin experiment.

1. No One-Size-Fits-All Diet

• Your body’s response to food is highly individual. Some thrive on fats, while others function best with carbs.

2. Athletic Performance and Carbohydrates

• If you engage in high-intensity exercise, carbs may offer better fuel efficiency and endurance.

3. Keto Can Be Beneficial for Fat Loss

• Fat-adaptation takes time, but once your body adjusts, you may experience consistent energy and reduced cravings.

4. Meal Variety and Sustainability Matter

• Long-term success depends on how sustainable a diet is. If a diet is too restrictive, adherence becomes a challenge.

Which Diet is Right for You?

Whether you should choose a high-fat diet or a high-carb diet depends on your goals, lifestyle, and personal preferences.

Who Might Benefit from a High-Fat (Keto) Diet?

– Those looking for rapid fat loss without extreme calorie restriction
– Individuals who prefer fewer but more satisfying meals
– People wanting stable blood sugar levels and reduced cravings
– Those with medical conditions like epilepsy, where keto has shown benefits

Who Might Benefit from a High-Carb Diet?

– Athletes and those engaging in high-intensity workouts
– People who feel more energized when consuming carbohydrates
– Individuals with no issues managing hunger or sugar spikes
– Those who prioritize meal flexibility and variety

Final Thoughts

The Turner twins’ experiment sheds light on how diet affects body composition, performance, and overall well-being. While a high-fat diet offers benefits like satiety and fat loss, a high-carb diet proves advantageous for athletic endurance and workout performance.

The ultimate takeaway? There is no universal best diet—it all comes down to personal needs, goals, and how your body responds to different macronutrient balances.

Before committing to a drastic dietary change, consider experimenting with both approaches to determine what works best for you. And as always, consult a nutrition expert or medical professional to ensure your chosen diet aligns with your health objectives!

What’s your take—do you thrive on fats or carbs? Let us know in the comments! 🚀

(https://www.menshealth.com/uk/nutrition/a63785050/high-fat-versus-high-carb-diet/)