But two identical twins had a unique chance to settle this debate once and for all in a real-world experiment.
In a 12-week study conducted with Kings College London, Hugo followed a vegan diet, while Ross continued eating meat, dairy, and fish.
To ensure that only their diets were influencing the results, they both consumed the same number of calories each day and followed the same workout routine.
“I think the first couple of weeks it was really craving and wanting meat and dairy and cheese. I love cheese,” he said.
He mentioned, “I was now having to eat fruit and nuts and alternatives that didn’t have any dairy in them – and so that meant I was eating a lot more wholesome food, which meant that my sugar levels were a lot satiated during the day. I felt like I had more energy.”
He felt ‘very energetic’ on some days but had ‘huge lulls’ on others.
This reduction in gut bacteria diversity meant Ross was less likely to get sick since his gut bacteria remained stable.
Hugo did see his cholesterol levels drop ‘off the scale’, which was a significant benefit.
Additionally, he lost weight and improved his resistance to type 2 diabetes.
This realization led him to reconsider some of his dietary choices.
In contrast, Ross gained ten pounds of muscle but also increased his body fat percentage from 13 to 15 percent.
The experiment highlighted how different diets can have varying impacts on different aspects of health and well-being, even among individuals with identical genetics.