It's the world's fastest-growing diet, but it doesn't involve calorie-counting, food-combining or exercise. With the Weigh Down Diet, all you have to do is pray yourself thin. Richard Johnson heads for Nashville to hear the good news. Photographs by James Rexrode
wen Shamblin is 5ft 4in, 7st 11lb, and an American size six - but it's not down to slimming pills. It's certainly not

down to exercise. It's down to God. Shamblin received her master's degree in nutrition from the University of Tennessee but - more importantly - she has loved God since she was a girl. The Lord of Heaven is her nutritional foundation.

"We are created with two empty, needing-to-be-fed holes in our body," she says. "One is the stomach and one is the heart. Only God can bring us to a peace with food. Binge out on God." Shamblin's Weigh Down Diet is now the fastest-growing weight-loss programme in the world. God, it seems, is moving in mysterious ways.

Religious diets aren't new: there's More Of Jesus, Less Of Me; there's Help Lord, The Devil Wants Me Fat. They are your basic low-fat diets with Bible study supplements. There's the Hallelujah Diet, advocating raw fruit and vegetables like those found in the Garden of Eden. And Jehobics, a way for Christians to exercise away unwanted pounds. After all, original sin was really a form of gluttony.

But only the Weigh Down Diet lets God-fearing men and women eat what the hell they want and still lose weight. Maybe that's why it's proving so popular. Shamblin has built an empire of 24,000 classes in only six years, and now it's in more countries than Weightwatchers.

Shamblin, 44, had problems with her weight at college. She recalls that she looked like "a potato with toothpick legs", and had started to fasten her trousers with safety pins.

One day she was in McDonald's with a thin friend. The friend left half her Big Mac because she was, well, full, and Shamblin set about studying the eating habits of thin people.

"My goal was to be a dietician in a hospital," she says. "Then I realised that food was my God. I knew God, but He wasn't everything. He was a portion. I enjoyed Him, but I loved His food more. Some friends said: `This message doesn't belong here. It belongs in church.' So I rethought everything."

The resulting Weigh Down Diet was common sense. Learn to distinguish false "head hunger" from true "stomach hunger" - eat only when you're physically hungry. Drink three ounces of orange juice to raise your blood sugar before you eat. Take smaller bites. Eat your favourites first - that way you're more likely to abandon the rest when you're full. But the common sense was underpinned by an unshakeable belief in God. He can help, if you're eating between meals and ruining your appetite. "Whenever people get tempted to snack," says Shamblin, "I say `Chew on this' - and I hand them a Bible. Run to the Lord - not the refrigerator."

To begin with, the church elders objected. They didn't like Shamblin being on such close terms with their God. This, after all, is Nashville - the heart of the Bible belt and home to the world's biggest Christian bookshop. "Sure," she says, "some didn't like it - the people who were `religious' but didn't have a real relationship with God. You have to know Him enough to come up with the concept that God loves brownies. That was revolutionary to America. The God I know is the God who makes the chocolate and throws in the fat. He stirs in the sugar. Luckily I'm female and non-threatening. Nothing about me looks religious, and I got in through the back door of the churches because of that. Then they saw the fruit of Weigh Down, and wanted me to stay."

The diet turns thinness into a sign of spiritual vitality. There's already a social pressure to be svelte - now it's a spiritual pressure as well. But Shamblin denies that Weigh Down is judgemental. "There are no weigh- ins," she says. "There are no measurements. In the first week I say, Don't judge the person that's overweight because you yourself may have a love of cigarettes, or a love of soap operas. We've all been in Egypt. [She compares dieting to the struggle to escape slavery in Egypt.] Religion is what you adore. Religion is what makes your pulse go up. Is it the buffet lunch at the restaurant? Or is it the Lord God Almighty?"

America's fat-acceptance lobby, who insist they're both fat and fit, aren't convinced. But Shamblin doesn't seem to care. "When these people have tried everything except God, and they can't lose weight, they give up. Then they start saying the rest of us have to change: `I'm going to force the stores to make bigger clothes. I'm going to force the airplanes to fit bigger seats. I'm going to make the world accept me, because I'm not going to change. I'm going to make my husband like me the way I am, and you'd better like me or else.' We're talking about some very intimidating people."

Shamblin was the cover-girl on Today's Christian Woman, and she's written recipes for Exodus, Weigh Down's in-house magazine. But now she's becoming more USA Today and the Washington Post. "I'm happy with the reception we're getting on television. A Current Affair [a TV news series] said, `Move over Jane Fonda. Make way for the new kid on the block.' I thought, `Oh no. It's going to be me.' Then they showed a picture of this beautiful church. The new kid on the block was God Almighty! I loved that." Her most recent success was Larry King Live. Now Ruby Wax wants to film her. "We're still praying about that," says Shamblin.

"I feel like the media are actually behind the times," she says. "They are uneducated. They don't really have a finger on the pulse. New York and Hollywood didn't realise that Touched by an Angel [a TV drama series that emphasises the spiritual aspect of life] would be the number one show of all time. They're realising that country music is popular. All the newspapers are suddenly doing a religious section. Their motives might be mercenary, but may Christ be preached."

Weigh Down is Shamblin's way of serving His house. But it's a profit-making organisation, and at $103 (pounds 65) for the 12-week course, it's serving Her house quite nicely as well. "God has led me to not live like a pauper," Shamblin believes. "Or to take the vow of poverty. He has led me to red meat, sour cream, and brownies.

"I said, `God, righteousness and having things don't go together.' Nothing about me looked righteous. I didn't home-school my kids. I didn't have all my hair cut off. I wore make-up. I was worried. But He was saying: `Look, not only am I filthy rich, I live in a big house.' I've told people before - God probably wears designer clothes."

For lunch, she drives me to J Alexanders, a dark restaurant next to Taco Bell. Shamblin is wearing red. He decided she should wear it. "Well," she says, "it happens every morning. God wakes me to see his sunrise. I go, `That's a good one, God.' I look outside, I say, `You put that grass colour with that grey and cream sky. You're the genius behind colour. You pull together my outfit.' I dress for him." Today He's gone for a red two-piece with contrasting gold necklace. It's smart but casual - just right for a lunch. It's no surprise to find that He also chooses what she eats: steak, fries on the side, and the chocolate cake to follow.

God will take away the sins of the earth - and Shamblin's desire to eat the second half of that steak dinner. All she has to do is ask. The Weigh Down Diet is about building that personal relationship with God, about feeling happy to trouble him with the details. It turns the problem of weight into an opportunity for spiritual growth.

Eat only when you're really hungry - it's called "the growl" - and stop when you're full. Therein lies the problem. Most overweight people just can't stop. "Leave the table and go into another room and pray for God to remove the desire to eat another bite," she says. "Give Him a few minutes, and He will answer the prayer."

Her steak looks good. A lot better than my salad. "God did not put sour cream or blue-cheese dressing down on earth to torture us," says Shamblin, with the enthusiasm of the cheerleader she once used to be. "He put them down here on earth for our enjoyment."

Shamblin eats whatever she wants, whenever she wants, as long as it's "between the green line of hunger and the red line of fullness". She picks at her steak. It's not joyous to watch. She only eats one-10th of what's one her plate, and gets the remains "to go". This is food as fuel.

We drive back to Weigh Down headquarters, on a concrete business park outside Nashville. It look like a crematorium. This is where Holland Baker, Weigh Down's outreach director, and her 34 phone operatives answer up to 2,000 calls a day. "Each call goes through to the right operative," says Baker. "That's the hand of God. If a call is going to take 10 minutes or less, it's for Outreach. More than that, it's for Counselling. A couple of people in Counselling do have degrees, but we prefer mature Christians with life experience. Then we pray together down the phone line."

Shipping is next to Outreach. It's where the fridge magnets, the audio cassettes and the Weigh Down T-shirts (up to a size XXXL) are freighted out around the world. Distribution manager Dave Taylor used to work for McDonald's. But then he discovered the Weigh Down Diet. He lost 50lb, hung up his stretch pants once and for all, and came to work for Shamblin. He's gone from managing stock in a two-car garage in Cookville, to this - a 40,000sq ft warehouse, with his own team of co-workers in matching blue polo shirts. It's the tail-end of the New Year's resolutions, and Weigh Down's busiest time of the year, but Taylor is likely to get busier.

The Otter Creek Church of Christ is a warm, welcoming place. OK, so we are covered in the blood of Jesus, but the pews are still padded and the hymns are nicely projected on to the wall. Shamblin worships here whenever she can. We sing four hymns, back to back, then it's off to night class. Churches in these parts are doing their best to look relevant, and offer Divorce Recovery on Monday, Faithbuilders on a Tuesday, and Weigh Down Workshop on a Wednesday. The approach has invigorated organised religion and brought new people through the front door. The hope is that they will sign up for Bible study before they leave.

Tonight's Weigh Down testimonials are enthusiastic. Debbie Collier used to take slimming pills. She smoked heavily. Now she's saved her marriage and lost 7lb: "But I've lost a total of 100lb off my evil heart." Jim and Glenda Hutchinson have lost 69lb between them. This is the fifth time they have done the class. They don't need to lose any more weight - they just like the Bible study and the sense of community. Now they bring their daughter, Jennifer, known as Fattie. "Before Weigh Down, Rollaids [ant-acid tablets] were just like candy to me," she says. "This has brought me back to God. It's an amazing way to spread the gospel."

Dani Waites was uncomfortable with the whole idea to begin with: "I didn't like calling on Him personally. It seemed too Holy Roller. I wasn't raised to go to Him. But I'd tried everything.

"I remember watching these overweight people in an infomercial. They were on a cruise. He was real excited. `Do you want to lose weight?' he asked her. `Yes,' she said. `Do you want to eat more food?' `Yes,' she said. `Do you want to eat more often?' `Yes,' she said. It was about eating more often to speed up your metabolism. But like the rest of us, I just needed to eat less." She found Weigh Down, and managed to lose 33lb. Now she runs her own workshop.

"I'm having trouble distinguishing `full' and `satisfied'," says one workshopper. Only the Lord can really help you distinguish. The Lord can do anything. To illustrate the point, a young girl stands up. She really wanted to hear "My Girl", then it came on the radio: "Then I was watching Designer's World. I thought, `Wouldn't it be cool if it was the one where they all went to Japan?' And it was." Dani smiles. It just shows God's attentiveness. Then we watch one of Shamblin's videos. Tonight she is in Egypt. Literally. For seven days she filmed her own version of Exodus, using the pyramids as a backdrop.

Now she's ready to free Britain from slavery. The first British Weigh Down Workshop opened two years ago in Ilford. There are now over 30 classes in the UK. The British Weigh Down market, however small, does exist, but they better understand the language of salvation in America. They aren't frightened by talk of the Holy Spirit. And there are Christian radio and TV stations in every city, preaching the gospel. In Britain, we worship differently. If the Weigh Down Diet isn't going to end up in the remainder bin, Shamblin needs to understand that

`The Weigh Down Diet', by Gwen Shamblin, is published by Doubleday/Gracewing, pounds 15.99