It's winter in Berlin - in other words, it's freezing. Outside it's minus 3 degrees Celsius (around 27 degrees Fahrenheit), and while I'd normally be wearing my fur-lined leather boots while drudging through the light rain, today I'm donning canvas Converse sneakers and leg warmers.

It's two days into my #HowGreenAmI challenge, living vegan for a week, and so I've been carefully trying to replace any animal-based products that have become part of my daily life with vegan alternatives - my wool jumpers with acrylic or cotton, meat with ...well, no meat.

It's tough. So far, all I'm feeling is resentment, and a deep desire for this experiment to be over - possibly a side-effect from also having to give up my morning tea.

As a Brit, I drink black tea with a splash of milk. And at the moment, I can't stomach the thought of trying my daily wakeup beverage with a rice or soy alternative. I'm not quite that desperate … not yet, anyway.

But others, it seems, have no problem. An increasing number of people are choosing to become vegan. Although global figures are hard to come by, in the United Kingdom - my home country - there are more than half a million vegans. That figure has risen almost fourfold over the last 10 years, according to a survey published earlier in 2016.

Being vegan is supposed to be better for our environment than a meat-based diet. According to research carried out on behalf of the United Nations Food and Agriculture Organization (FAO), the livestock sector is responsible for almost 15 percent of human-induced greenhouse gases.

Feed produced for the animals, transportation of the animal products, and expansion into forests for pasture and cropland for feed all contribute to emissions - and therefore to climate change.

And as the global population grows, this is only going to get worse. Demand for meat and milk is also expected to grow by 73 percent and 58 percent by 2050 compared with 2010 levels, according to the FAO report.

Berlin - vegan capital?

But luckily for the environment, and for me, veganism is also popular in my adopted home - Germany - where there are estimated to be almost a million vegans.

Around 80,000 of those live in Berlin. Here, there are vegan restaurants, clothing and even vegan sex shops - so at least I'm in the right city for my experiment. Or so I thought.

"Go on, just have some meat, nobody will know!" are the words of my so-called friends. Three days in and I'm joining them for a group dinner. Upon making the booking, none of them knew I would be vegan for the week. And the choice couldn't be worse: This particular restaurant serves more or less only cheese fondue and grilled meat.

I look over the menu again and pick out pumpkin soup, careful to ask for it without cream, and some fries. While my friends laugh and jest as they fight over who will be first in dipping bread into the melted cheese, I sit back and tuck into my single meal. I have to admit, I feel a little left out - and I don't even like cheese.

Still, at least we were all able to share a bottle of wine together … and here is where I should perhaps point out my cheat of the week.

You'd be surprised how much we depend on animal products - milk, eggs, and animal products are hidden in much of our foodstuffs. To my horror, I discovered milk protein in my favorite crisps, and eggs in mayonnaise and a variety of different sauces. Then there's the wine.

Making wine involves a refining process which is often carried out using fish bladders, gelatin, casein (a milk protein) or egg whites. However, whether it is vegan or not is often not displayed on the labeling.

The only surefire way of knowing your wine is morally upstanding - vegan-wise - is to buy brands with a vegan label. A fact I willfully turned a blind eye to throughout the week. Ignorance is bliss.

Veganism = deprivation?

As the week wears on, my will to stick with the challenge begins to diminish. A vegan restaurant I visited with friends did nothing to stave my cravings for chocolate despite the delicious-looking desert - it seemed flavorless in comparison to the milk chocolate I'm used to. And the cotton and acrylic scarves are failing to hold back the biting cold.

I need to hear from some people who practice a vegan lifestyle, and find out how they live with what I can only describe at the moment as deprivation. Luckily, at the end of the week is a vegan market where I can ask my questions.

The founder of Green Market Berlin, Stefanie Witt, tells me that she first became vegan three years ago for health reasons. "I had epilepsy, and I found out that if I ate a healthy vegan diet, that the illness can disappear. And it has. I don't have to take any more medication."

Health benefits are certainly something I could get behind, but what about other reasons for being vegan? Stallholder Monique, who is selling vegan lip balm at the market, says her reason for becoming vegan relates to animal welfare.

"I was a naggy meat-eater. I would eat it and love the taste, and then I would think about those poor animals … and that went on for years. At one point, I thought: Okay, either stop nagging or just stop eating all this stuff," she said.

From strict to flexible

I'm torn. I'm also concerned about animal welfare, but I don't absolutely oppose animals being slaughtered for food. It is rather the industrialization of the meat industry that has given me pause.

And the climate impacts of meat-eating are also a worry for me. Yet I'm not completely convinced that a vegetarian diet, rather than a vegan diet, might be just as good or better for the environment.

If you're vegan, you are no longer eating livestock or dairy products, which contribute to emissions - but it also means replacing wool and other animal products used in clothing with synthetic fibers made from fossil fuels, and which are polluting the oceans.

I'm also concerned that even if I were to become vegan, perhaps I wouldn't be able to keep up such a strict regime. But every little helps, right?

"What I don't like about the vegan scene is when people tell you how you should live," Monique tells me. She admits that despite being vegan, she's held on to her leather bags and jacket. "I make my own rules. Why should anything have rules for what comes from a pure heart? I want to make an effort and contribute as well."

Cutting down on meat and animal products is something I can definitely do. And who knows - maybe in the future, I'll even try visiting veganism again for an even longer stay.