We’ve all heard of people who have gone to extreme lengths to lose weight, and of people who’ve had success on what seems like a crazy diet. But do desperate times truly call for desperate measures? Our Trainer-in-Chief Jessi Kneeland gives you four of those diets — demystified and debunked.

1. Paleo Diet or “Caveman Diet”: Based on the principle that humans have not evolved fast enough to handle our modern “agricultural revolution-based diet,” and are better off eating foods that could have been hunted or gathered in the Paleolithic Age. It consists mostly of lean proteins like fish, eggs, and grass-fed pasture raised meats, natural fats like coconut, avocado, and nuts/seeds, plus lots of vegetables and some fruit. It excludes all grains, legumes, dairy products, salt, refined sugar, soy, and precessed oils.

Busted: This one actually gets my approval. I’m not so into the “we should eat like cave-people” aspect, but the foods themselves are easily tolerated, low-inflammation foods that give you the right amount of fats and proteins, as well as plenty of antioxidants and necessary vitamins and minerals. This one is a “way of life” diet, not a weight loss diet — and it requires cooking and preparing your own foods, which is super wallet-friendly!

2. hCG Injections: The hCG (human chorionic gonadotropin) hormone is supposed to suppress hunger and trigger your body’s use of fat for fuel, although most hCG diet plans restrict calorie intake to 500 calories per day as well. Proponents of this diet say you should stick with the plan for 30-45 days, and the claim is that you can lose 1-3 pounds per day.

Busted: The injections don’t have a lot of scientific evidence behind them, and their claims are mostly unsupported. I also wouldn’t advise ANYONE to follow a 500 calorie per day intake, and I seriously question why someone should have to, especially if they’re getting these “magic fat-burning” injections at the same time. The side effects of the injections themselves are bad enough— headaches, dizziness, depression, and blood clots—but the side effects of such a low calorie diet are destructive and irresponsible. Malnourishment, low blood sugar, and the metabolism slowing way down: that doesn’t sound like an effective or healthy diet to me. The verdict? Save your money.

3. Zen Diet: Based on the food rules that monks follow, the Zen diet is traditionally vegetarian, with no meat or fish, and no “strongly flavored foods or spices.” The food is prepared simply and aims to include the five flavors (sweet, sour, salty, bitter, and hot) along with the five food colors (green, yellow, red, white, and black) and five types of cooking (frying, boiling, roasting, steaming, and fresh). It suggests cooking with in-season foods when available, and using all edible parts of each food in order to practice living in “humble poverty.”  Emphasis is placed on gratitude and appreciation for the food’s presentation, as well as taste.

Busted: Anyone who trains with me knows that I typically don’t support vegetarianism — I think it’s too difficult to get the appropriate amount of protein from non-meat or fish sources. (And I don’t consider soy or tofu an acceptable alternative, as it’s highly processed and is an estrogen-booster, which can cause health and hormone problems.) But the Zen Diet places a major emphasis on appreciating your food, which I imagine would slow down the eating process and cause someone to eat more consciously and sensibly. I’m all for anything that makes you relax and feel gratitude for your body and its fuel sources, and I think if we all spent more time considering and appreciating what we put in our mouths, we probably wouldn’t go around mindlessly scarfing down fast food and other junk. So in this one case, I’ll make an exception for the vegetarianism and give this one my stamp of approval. Plus, in-season foods and local markets mean “humble poverty” will actually save you cash!

4. Feeding Tube Diet: A feeding tube is hooked up to a person’s nose, and a mixture of fats and proteins (in liquid form) go straight to the stomach. It gives a total of 800 calories per day, and the feeding tube stays in for 10 days. $1,500-$2,000 for the full 10-day treatment.

Busted: Say what?! I am shocked that this even exists. It takes away the entire process of eating and of food, and is exactly the opposite of “eating consciously.” I think the nutritional value of this diet is probably higher than that of say, the grapefruit diet, but that doesn’t make it a good idea. When the person starts eating real food again, she will still have all her emotional and habitual ideas about food in tact, and nothing will have changed. She will gain the weight right back, and will probably always believe that without some magical extreme measure, she can never look that good again. It takes the power out of her hands, and I think it will be impossible for a lasting change to be made. It works, obviously, in a very short-term way, but it’s disempowering and doesn’t teach the person how to make real progress or lose weight in a way she can maintain. No way, especially with a pricetag like that.

5. Master Cleanse: Made popular by Beyonce, this is a “juice fast” that includes a salt-water flush every morning, a laxative tea every night, and no food; just the mixture of maple syrup, lemon, and cayenne pepper with water all day. It lasts a minimum of 10 days, and claims to detoxify and purify the body, as well as help you lose weight, fight aging, and make you feel happy!

Busted: While this one would probably save you a ton of money on groceries (the only benefit of fasting, as far as I’m concerned), the health benefits are dubious. The lack of calories will be enough to lose weight, but it will mostly be water weight and muscle at first. Also, there is no evidence of any anti-aging benefits, or even  that our bodies eliminate more toxins with a “cleanse” diet than they would through normal bodily functions!  Add in the backlash binge when you go back to normal food, and the fact that your digestive tract will be “cleansed” of good bacteria when you’re finished, and I can’t imagine this cleanse leaving anyone happier.

Jessi Kneeland is an NYC-based personal trainer. She believes that fitness can show people what they’re made of, including our own Recessionista-in-chief, who’s bum Jessi kicks daily. Check out her blog at http://jessikneeland.wordpress.com/ or drop her a line at jlk399@gmail.com.