The Turner Twins are no strangers to physical dering do. As explorers and adventurers, their latest challenge was not to the Green Pole, but to the diet poles, testing opposite ways of eating: The vegan or plant-based diet versus a meat-based diet. It was an "inner" journey of monitoring their blood levels, body fat, and weight, along with workout fatigue, training recovery time, and how they felt. Spoiler alert: After 12 weeks, the vegan diet kicked the meat-based diet to the curb.

At the end of the 12-week experiment, the identical twins detailed their methods and results. It's not the first time they have tested diet plans, they told Men's Health UK.

Said Ross: "At the end of last year we did a test of high-fat vs high-carb. I was on the high-fat diet and I shredded. I lost about 3kg of fat; Hugo was on high-carb and he put on 3kg. Adds Hugo:  Ross has always been slightly heavier, so, we met each other in the middle [when I was on that high-carb diet.] In the end, we were 85kg each.

Hugo Goes Vegan, Ross Keeps Up the Meat. Here's What Happened:

Introducing the vegan diet vs. the meat diet 12-week challenge on their YouTube channel, in January, the Turner Twins explained that they worked out together at the gym, on the track, and on their bikes, and measured their body fat and biomarkers at the beginning of the 12-week diet experiment, and reported on their results in Men'sHealth UK.

Ross and Hugo Turner call themselves "adventure guinea pigs." In this experiment, they discovered dramatic differences in how they felt on the two diets. Their findings: Hugo, on the vegan diet, had better energy levels for training and lost more body fat, while Ross on the meat diet, felt fewer changes (no surprise since he basically kept eating his usual omnivore diet) and his body fat was more stubborn–it actually went up slightly. They measured their gut microbiome and cholesterol levels, two important markers of current and future health that can predict the risk of heart disease and other chronic ailments.

The vegan diet helped in all areas except one: The only drawback was that Hugo felt hungrier some of the time, they explained. In an interview with The Insider.

The Turner twins go on an expedition to the edge of the diet frontier

The Turner Twins have climbed countless mountains and trekked to the most unhuman points on every continent, raising money and doing research as they go. For this diet adventure, they tested the role of fuel on two identically genetic bodies.

Identical twins, identical workouts, very different diets: Vegan vs. meat

What makes this diet more interesting to science–other than the obvious fact that it had only two people in the study-- is that they are genetically identical and they trained the exact same way for the three months. Originally they were inspired by the athletes they saw successfully trying plant-based diets in the documentary The Game Changers, Ross explained.

"We wanted to take bias and opinion out of it and take it down to the genetic level. We can get science involved because we're twins and genetically identical, so we can compare ourselves in extreme environments," Ross said In an interview with Insider.

The twins, who live in the UK, worked with Kings's College to track their health metrics such as weight, cholesterol, and muscle mass. Hugo and Ross continued their usual endurance training five to six times a week, using a program designed by Ross, who is also a personal trainer. They ate an almost identical number of calories in meals prepared by the Mindful Chef.

After 12 weeks, the differences in muscle gain, fat loss, and digestive health:

The Vegan Diet:  Higher energy, less fat.  Hugo started the diet weighing 185 pounds with 13% body fat. After a month he had lost 9 pounds, although he regained some of those by the end of the experiment. At the end of three months, he weighed 181 pounds. Nearly all the weight lost was fat, with his overall body-fat composition went down to 12%. His cholesterol levels dropped and his energy level improved. Hugo said he felt significantly more alert and able to focus during his gym sessions, compared with his typical routine.

"On a vegan diet my mental focus was much better, I didn't have the mid-afternoon energy dips, and felt a bit more charged," he told Insider. On a vegan diet he changed his snacking habits, switching out chips and cookies to fruit and nuts.

The Meat Diet: Ross gained more mass overall Ross has always been the bigger twin, and this diet experiment only emphasized that. He started with 13% body and put on 10 pounds of muscle, in addition to just over four pounds of fat, with his body fat percentage edging up to 15%, and his final weight to 189 pounds. His cholesterol levels stayed the same. The diet meal plan was more varied than his typical diet, with an array of chicken, fish, red meat, veggies, dairy, and grains. Before the diet, the twins would always eat the same things: toast or oatmeal for breakfast, a sandwich for lunch, and chicken, veggies, or pasta for dinner.

The vegan diet led to changes in the gut microbiome

For Hugo, the vegan diet was a bigger chance, since he swapped out meat for tempeh, tofu, and jackfruit.

"Eating a vegan diet, you almost have to overcompensate with variety, so I was eating foods I wasn't really used to," Hugo said. The result was a change in his microbiome, which can potentially protect individuals against some forms of chronic illness, according to studies that show the vegan diet lowers the risk of heart disease, obesity, and type 2 diabetes.

But to their surprise, both brothers saw a decrease in their microbial diversity or the number of different bacteria in the gut. Although Ross' microbiome changed slightly, it remained much more consistent than Hugo's did. The sudden change to a vegan diet, and the short duration of the experiment, could have been the reason that Hugo saw the biggest changes, they hypothesized.

They plan to add more vegan foods into their diet, especially snacks

The 12 weeks wasn't long enough, the Turners said, to see the outcomes of dietary change on the body long term. They said they wished they had continued for six months or a year.

The twins said that after this trial they will incorporate more plant-based eating into their diet, including vegan meals, days, and snacks.  Knowns for their expeditions, the brothers want to test how vegan eating could benefit their energy and focus on a trek.

"You lose about half a kilo of weight a day on an endurance trip, and more than that if you're carrying extra weight," Hugo said, "so we like to be lean and mean and nothing in between on the trip."

He added that eating vegan for three months expanded his world of food options. "One thing to come out of this is we don't eat nearly enough variety of foods. Often, we kind of just disguise the same foods in different forms," Hugo told Insider. "But variety is the spice of life."


Try it, by adding in vegan snacks, meals and days to your diet, the Turners advise

"Don't go "cold tofu" and jump in all at once," adds Hugo, who recommends starting with snack habits, and swapping out between-meal treats with vegan snacks like nuts, seeds, and dried fruit. The twins concluded that the optimal diet is a mix of both diets.

There tends to be a reluctance for meat-eaters to try vegan foods, Ross pointed out and he wants to encourage meat-eaters to add more plant-based meals, like vegan burgers and other non-meat meals to their diet.

"Having a vegan diet has benefits and so does eating meat. I don't think either outshone the other here," he said. "We'll be doing a mix of both, having non-meat days and adding more vegan foods into our diet, eating better-quality meat, and less of it. We've taken away the best of both worlds."

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