Bernstein says his diet is 100 per cent medically supervised and it's about more than just counting calories.

"We use a lot of vitamins and minerals on our patients and we have a unique feature. Some of our vitamins are given by injection."

Clients are injected with a combination of Vitamin B6 and B12, three times a week. The idea is that the vitamins work to break down the fat.

"The B vitamins make it easy for someone to stay on a diet," Bernstein said. "I find that they enhance the weight loss. Our patients are losing between four and five pounds a week."

That's the big draw: rapid weight loss. It comes with a price tag. The initial consultation ranges from $195 to $235. Add to that $100 per week for services and injections.

Bernstein says an average patient who loses about 35 pounds will wind up paying about $1,000.

Every new client is given the Dr. Bernstein Diet manual and recipe book. Inside, there is a very specific list of foods you can and cannot eat. There are also daily menus.

Bernstein says most patients are allowed between 850 and 950 calories a day. He says there are really no side effects.

Diet experiences mixed

Mike Bullard told Marketplace that he lost 56 pounds on the diet. "I was very happy with the result and there were no health repercussions for me."

Marketplace spoke to 40 of Bernstein's clients. Their experiences were mixed.

Richard Lumb lost about 30 pounds in two months. "I was constantly light-headed from the diet and constant nausea. I just generally felt unwell."

Sofie Kosmas, who dropped 35 pounds, reported migraines and dry, flaking skin. "I was nauseous all the time and…that went on and on and on until I saw my family physician who demanded that I stop."

Gloria Nixon is still on the program and has 14 pounds to lose before she reaches her goal. "I've been losing about ten pounds a month. Ten to 12 pounds a month."

Marketplace went to leading weight loss experts for their opinions on the diet, but Canadian doctors were not prepared to talk on camera.

But at the Harvard Medical School in Boston, we met with Dr. George Blackburn. He's an internationally recognized expert in obesity and clinical nutrition. He lectures at Harvard and runs several weight loss clinics at a Boston hospital.

"Any time you're eating less than a thousand calories and losing more than two pounds or three pounds per week, you would be in semi-starvation mode and that would require medical supervision," he says.

Blackburn adds there are several dangers to rapid weight loss, including:

• You may get sick — suffer from dizziness and feel light-headed
• Possible gall bladder attack
• The faster you lose weight, the more likely you are to regain it

Bernstein says his diet should not be classified as a Very Low Calorie Diet.

"The definition of a very low calorie diet…is under eight hundred calories. Our diet is between 850 and 950 calories."

Bernstein client Sofie, who lost 35 pounds, says she was never told how many calories she was limited to. She told us that she and her doctor sat down one day, did the math and came up with about 500 calories a day.

Marketplace asked registered dietician Marilyn Cowling to add up the calories in the food recommended over two days of menus supplied in the Bernstein diet book. She came up with 450 to 500 calories per day.

The instructions in the book warn: "Even the slightest deviation may be detrimental to your success."

Marketplace initially spoke to 40 Bernstein clients. Of those, we re-interviewed 22. Six told us they were allowed to eat more than what was specified in the diet manuals. But the majority said they were told to stick to what was in the diet book or to eat less, if they weren't losing weight quickly enough.

Injections help weight loss: Bernstein

Bernstein says he offsets the rapid weight loss and limited caloric intake with the vitamin injections.

"Most safe diets should be losing a pound a week, a pound and a quarter a week. But with the help of the B vitamins and the oral vitamins and minerals we're using, patients can lose more weight, they burn fatty tissue up more aggressively."

But is there scientific evidence of that? "There is not specific literature that will tell you that B vitamins are going to burn off fat," Bernstein said. "But there are a lot of articles about B vitamins being important for metabolizing food."

Harvard nutrition expert Dr. George Blackburn says the injections are like an electrical stimulus: "It's something to remind you that you're on this program and you want to be compliant to it. It's used as a motivator to make people adhere to the diet, in this case."

There's another motivation technique: A firm approach. "He would chastise me, and then, and then he would say, if I got headaches or if I wasn't feeling well, 'well you're cheating.' Well, no I'm not cheating, and we would have this back and forth," patient Linda Siokalo told us.

Bernstein denies yelling at patients. "We're tough. We're friendly and we're tough. But tough means come to us, follow our regime, we'll teach you what to do, we'll teach you how to eat properly and we don't take excuses," Bernstein said.

Fat: more than meets the mouth

The fat content of the Bernstein diet is not restricted to what you put in your mouth. It also includes soaps and creams.

Clients are restricted to cream-free soaps and hypoallergenic or water-based creams. In fact, he offers one on his website, specially designed for dieters. The package costs $159.99. But there's a special offer for Bernstein clients .

Who makes these products? Bernstein's wife, Judy. She's the president of a cosmetics company.

"We know that a lot of fatty elements on the skin, a lot of fat oils get absorbed through the skin. I keep my diet as low in fat intake as possible, both orally and on the skin," Bernstein said.

Sofie, Richard and Linda all left the program. They've gained back all the weight they had lost. Richard says his impression of Mike Bullard has changed.

"It's tough to say that Mike Bullard or any other individual, that the onus is on them to do extensive research and to make sure that their individual case is representative. A diet that would work for him may not remotely work for somebody else," Media Watch's Shari Graydon said.

As for Bullard, he says exercise has been a big part of losing weight and keeping it off. Exercise is not listed as a necessary part of the Bernstein diet.

"I have never said that I would recommend this to anybody, because to be a person who goes on a diet, to be a person who sets about a life change, you've got to be stable. You know, you can't recommend it to just anybody out there," Bullard told Marketplace.

Bullard adds his responsibility as a celebrity who endorsed a product ends after using the product successfully.

Neither Health Canada nor the Ontario Ministry of Health regulates diet clinics. When we contacted the Ontario College of Physicians and Surgeons, we were told it would not comment on a specific doctor.

Bernstein says that business is booming, thanks, in part, to his ad campaign and Mike Bullard. He's expanded from 14 to 27 clinics, all but one in Ontario. A Bernstein clinic opened in Richmond, B.C. last November. Bernstein says further expansion is very much on his mind.

What do Monica, Sarah and Mike have in common? The celebrity seal of approval did not come for free. Bernstein says Mike Bullard was paid for his kind words. All Bullard would tell us about that was, "No comment."

If you are thinking about shedding a few pounds and you see Mike Bullard's ads for the Bernstein Health and Diet Clinics, look beyond the famous face and make sure it's right for you.