How does eating vegan diet for 30 days impact your body?

With a new year comes new year's resolutions, and I challenge you to find someone who doesn't start their list of goals with 'be healthier.'

After a festive season full of drinking, many of us have said au revoir to alcohol as we embark on Dry January - a campaign started by Alcohol Change UK to encourage people to consider whether their relationship with booze is a healthy one.

Others have signed themselves up for a meat-free month in hopes of reaping in the benefits of a plant-based diet, also known as Veganuary.

Professor Natalia Lawrence says: "We know that reducing meat intake can have a number of benefits including on health, the environment, animal welfare, and on finances."

To fully put the vegan lifestyle to the test and see if it actually has the health benefits that everybody claims, Matt from YouTube channel Yes Theory decided to take on a 30-day vegan challenge - and the results are pretty shocking.

Prior to starting the challenge, Matt had a full set of blood tests done so he could see what impacts the diet had and consulted with expert dieticians along the way.

He also discovered a lot of misconceptions relating to veganism, including concerns about it causing nutritional deficiencies.

Documentary-maker James Wilkes told him: "A lot of people that go vegan just aren't educated on how to do it. You can't just take your current diet, take meat off the plate and think you're good to go.

"But, if you look at nutritional deficiencies, on average vegans are deficient in four nutrients. Meat-eaters are deficient in nine."

But what changes did Matt see in his body after 30 days of veganism?

"I don't feel worse. That's the main thing," he said.

And, his repeated blood tests showed some marked improvements.

"We actually a pretty sharp increase in your testosterone," his doctor told him. "Whether or not the vegan diet is right for you, this is a huge positive benefit.

They also saw improvements to his vitamin B12, thyroid, iron and protein levels.

Matt later admitted: "I did not expect the results to be that good. It's actually quite shocking. I kind of feel like I don't have a choice but to go majority plant-based now the results were better after and I was already eating so healthy before.

"I think I'll still have some animal products once in a while but mostly plant-based."