British businesswoman and columnist Katie Hopkins has a controversial view on the obesity epidemic: that the solution is simply to eat less and exercise more — and that fat people have no one to blame for their weight issues but themselves.

And she’s willing to put her own body on the line to prove her point — eating an average 6,000 calories a day for 12 weeks and then losing the weight — in a journey that’s documented in the two-part TLC special “Fat and Back,” premiering Sunday at 10 p.m.

“Watching ourselves get bigger and bigger isn’t really something that I’m OK with,” Hopkins tells The Post. “It disappoints me, and it seems that whatever solutions we’re trying at the moment — which seems to be a lot of tea and sympathy — isn’t really working. And I suppose that’s where my approach comes in, which is a little more tough love.”

Her harsh brand of fat-shaming has even seen Hopkins beat out the acerbic Simon Cowell in a poll of the UK’s most unpopular celebrity for her eyebrow-raising statements, like saying she would not hire someone who was obese because they look lazy.

To transform her trim, 124-pound figure into a pudgy one, Hopkins began by eating 4,000 calories a day, but didn’t put on any weight in the first two weeks because she was technically underweight for her frame. By a month in, she upped her daily caloric intake to a staggering 6,500 calories — equal to 13 meals a day (see sample menu below).

“It was essentially getting up and knowing that every two hours I would be eating a main meal,” she says. “In the end it got to a point where I didn’t like waking up in the morning because I knew that my day was [going to consist of] doing the thing that I didn’t want to do.”

The normally active married mom of three also had to keep her movement to under 1,000 steps a day, which proved difficult on her family.

“For my children, that meant I wasn’t very fun to be around. I didn’t make an effort anymore in what I wore because I just wore big, baggy stuff that I bought in the supermarket,” Hopkins says. “My husband probably does deserve an award . . . our relationship suffered because I didn’t want to be naked anymore, I was a pajama queen all of a sudden.”

Her parents and friends — as well as medical professionals — also didn’t understand why she would voluntarily do this to her body, and advised against it. Through the weight gain, Hopkins became a person she didn’t recognize — one who felt weak, depressed and vulnerable.

“I signed up for this thinking this would be a physical process. But actually it turned out to be much more of an emotional journey,” she says. “I’ve had two weddings and I didn’t cry at those, had three babies and I didn’t cry at any of those childbirths. I don’t cry easily but this reduced me to tears loads because I just became a person that I’m not. I realized that actually being fat is hard.”

Making her feelings of vanity more difficult was the fact that Hopkins had to keep the show a secret, so she had no excuse to give for why she was suddenly gaining weight. Many assumed she was pregnant — she even got sent flowers for the baby and offered seats on the subway.

By the end of the 12 weeks, she had consumed 504,000 calories in total — enough for two women and a small child — and weighed 167 pounds, or a gain of 43 pounds from her starting weight.

When Hopkins set out to shed the pounds, she took an everywoman approach — she didn’t count calories or weigh herself — and simply ate what she wanted in moderation, which equaled about 1,500 calories a day. She used a pedometer to walk 20,000 steps daily and went for an hourlong run three times a week.

To combat criticism that it would be easy for her to lose the weight because she gained it quickly, Hopkins started a fat club with four people with long-time weight issues, who lost 90 pounds among them in five weeks.

“None of us had a gym, a personal trainer, we didn’t pay for anything, we just went out walking,” she says. “That’s the message for me — this doesn’t have to cost you anything but you can make a difference.”

After three months, Hopkins weighed 136 pounds, or about 12 pounds heavier than at the start. (Despite the wishes of friends and family who thought she was too thin before, she is now down to 130 pounds.)

“There are a lot of things now that I get that I didn’t get before,” Hopkins says of the experiment. “Telling someone who’s overweight or fat to put on a pair of trainers and get out there and get running — that is not going to work. Because when you’re fat you do not want to go running all over the place, carrying all that you are on your knees.

“But I still have a sense of tough love. I know how tough it is, but I feel like I have proved if you make a determined effort, you can beat it and you can really make a difference to your life.”

Hopkins has also not budged on her more controversial opinions, including that parents should be held responsible for having fat children and her opposition to people being allowed to get weight-loss surgery through the UK’s government-provided health coverage. And she still won’t hire someone who is overweight.

“While some of me has softened because of this emotional journey, and some of me understands being fat a whole lot better than I did,” she says, “also some of me has toughened behind some of my opinions and stands by them.”

Katie’s sample daily diet (6,500 calories)

8 a.m. Breakfast

Full English breakfast (sausage, bacon, fried egg, hash browns, fried bread)

½ liter chocolate milk

10 a.m. Second breakfast

Macadamia nuts

Croissant

12 p.m. Snack

½ can of Pringles

1 can of Coca-Cola

2 p.m. Afternoon snack

Dairy milk

½ liter chocolate milk

Chicken, bacon and mayonnaise sandwich on white bread

4 p.m. Late afternoon snack

½ liter chocolate milk

Chocolate bar

6 p.m. Dinner

Fish, fries and peas

½ pint of lemonade

Chocolate cake with heavy cream

8 p.m. Tea

½ can of Pringles

Cheese on toast

10 p.m. Late night snack

1 liter chocolate milk