After the Dukan, get the skinny on the OMG diet

You've heard of Dukan, scoffed fat on Atkins, fainted from drinking only honey and lemon water and lost friends from the noxious side-effects of the cabbage diet. Now there's a new one, this time designed to inspire jealousy and help you to "get skinnier than all your friends". Six Weeks to OMG comes out in print next month. It has knocked the Dukan Diet off the top of the iTunes diet book chart and a subsidiary of Penguin has bought it for a seven-figure sum.

The book, by British sports scientist and personal trainer Paul Khanna, who goes by the pen name Venice A Fulton, offers controversial tips, such as skip breakfast, take cold baths and drink black coffee. But for short-term weight loss, can the OMG diet really help you shed pounds? Consultant Dietitian and Sports Nutritionist Linia Patel, Dr Christian Jessen, the presenter of the Bafta award-winning Embarrassing Bodies series, and the celebrity fitness trainer Jay Darrell Ingleton explain the science behind Fulton's unconventional theories. I've also given Fulton's tips a try, in a (highly unscientific) experiment, to see how tough they are to stick to.

Skip breakfast

Fulton says skipping breakfast will help to stop you becoming a "fadult" (that's a fat adult to you and me). "Breakfast is for wimps!", he writes. He recommends exercising first thing in the morning on an empty stomach and then only eating once three hours have passed, so that your body is forced to burn stored fat rather than food.

The expert view: "Skipping breakfast is a weight-loss disaster," says Patel. "When you wake up your body produces cortisol, a stress hormone that helps store fat. If you don't eat, you are putting your body under more strain and stress and therefore more likely to gain weight around the middle. Also, you will want sugary and fatty things when you're really hungry, which add to weight gain."

My experience: I skipped breakfast and still had enough energy to run up the stairs on the underground (my "workout"). It didn't affect my concentration and I ate breakfast at 10am. It was easy, but I consumed exactly the same amount that I usually eat, so I doubt it made much impact on my weight.

Drink black coffee before exercise

Fulton says the caffeine in a cup of black coffee will help to boost your exercise routine: "It's nature's cheap and secret potion," he writes. But he warns against adding any milk or sugar to your drink, because "either would tell your body that food's arriving," which, in theory, will prevent it from burning its fat stores.

The expert view: Dr Christian Jessen says coffee can help, but there's no secret trick to it. "After 12 hours or more of filming, mustering the energy to get to the gym can be hard," he says. "Coffee gives me the energy to just about squeeze in a workout. It's a stimulant and that's what I use it for, but it doesn't make your workout more efficient." He also warns that liquids contain calories too. "People forget fluids such as the Starbucks coffee mocha creamy coffee thing can be high in calories. Adding milk and sugar to coffee will add to your intake. Remember your hard work in the gym is lessened by a highly calorific drink beforehand."

My experience: It made me feel more energetic, which probably helped to psyche myself up for the gym.

Take cold baths

Fulton recommends taking baths of between 15C and 20C to "help you lose calories fast". He says the cold boosts adrenaline, which he says is particularly good for burning the fat stored in women's thighs.

The expert view: Ingleton says that a lot of athletes will take ice baths to help their muscles recover. "When athletes do it after a workout it gets blood to the muscles quicker. It has to be freezing otherwise it won't work, but the author is not saying go to that extent. Also I don't think everyone will be working out like a top body-builder. For normal people, it probably won't make much difference to weight-loss."

My experience: I opt for a cold shower, which is horrible. It feels like my body is in shock and makes my heart race. Afterwards, my skin looks bright and glowing and my clothes feel really warm, but the results don't outweigh the awfulness. I couldn't stick to it every day for six weeks.

Eat less fruit

Fulton says you should eat as little as one piece of fruit a day during the diet period, although after the six weeks are up he encourages more balance in your diet.

"Fruit can be a cheeky devil," he says, because it contains fructose, which can turn to fat if it isn't burnt off.

The expert view: "It's all about calories," says Patel. "We recommend you eat five pieces of fruit and veg a day, but if you want to lose weight have more vegetables than fruit, as fruit is more calorific. It's ridiculous to just eat one piece of fruit a day for six weeks, because you're losing out on essential vitamins and minerals."

My experience: I replaced fruit with colourful salads and felt fine, but I missed having a late afternoon snack and bought a coffee loaded with honey instead of fruit – Fulton wouldn't approve.

Swap broccoli for Coke

Fulton says eating unhealthily in the short-term is OK if it makes you thin. "[For some people] to get skinny", he writes,"it makes no difference whether they get their daily carbs from cans of Coke or from broccoli... for six to 12 weeks there's no harm in using this knowledge to get super-skinny."

The expert view: Patel says: "Broccoli is a fibrous carb that helps digestion and gives you nutrients. If you lay off fibrous carbs like bread, pasta and vegetables then you will be constipated with no energy."

My experience: I'm far too fond of vegetables and regular bowel movements to attempt this one.

Duelling diets

If you don't like the sound of OMG, there are other diets that also promise fast weight-loss, but Dr Jessen warns that we shouldn't expect miracles: "Coming off the diet and coming back to normal is when the weight can pile back on. Dieting should be about taking a healthy, sensible approach that will work in the long-term. Don't try to cut everything out at once. Life is about enjoyment, too, and that's why you work hard, so you can indulge in a cheeky cake in the afternoon if you fancy."

The Headspace Diet:

10 Days to Finding Your Ideal Weight (Hodder & Stoughton). This is where you think deeply about every mouthful you eat and therefore, the theory goes, consume less.

"Being mindful while you eat is great, as most people tend to eat until they are stuffed," Patel says. "It takes about 20 minutes for the stomach to signal to the brain its full – but most of us can polish off two platefuls in less than 10 minutes!" But she warns that this diet has its risks. "Eating a tiny portion each meal, you would risk not getting in enough nutrients to keep you healthy."

The Baby Food Diet

This involves just eating jars of baby food in place of your normal, adult-size meals.

"Baby food is full of nutritious vitamins, which are easily digestible," Ingleton says. But he warns it's hard to feel satisfied with the lack of texture, and it's easy to go over the three-to-four jar allowance and overeat.

The Raw Food Diet

"The raw food diet contains fewer trans fats and saturated fats than general Western diets and it can lead to weight loss and may give you more energy," Ingleton says. He warns that there is a risk that the diet lacks some essential vitamins and fatty acids, so you would need to take vitamin supplements.

The Blood Group Diet

Devised by Peter J D'Adamo, this is when you cut out dairy, meat, wheat or grains depending on your blood type.

"There is no reasonable scientific basis for this," Ingleton says. Patel agrees: "You risk getting an unbalanced diet if you are cutting out a whole food group."

The Dukan Diet

Like the Atkins diet, the Dukan diet involves eating mostly protein for a few weeks and then gradually introducing other foods.

"It's a high-protein diet, so while it might work for some to kick-start weight loss it won't work for all, as it's hard to cut out carbs," Patel says. "You risk having low energy."