Are you trying to shed a few pounds and it's not working? Maybe you're just not thinking hard enough. At least that's what one group of mental experts say.

The Sudoku Diet -- named after the brain-twisting game that uses numbers and logic, is based on the premise that challenging the mind with difficult puzzles can burn 90 calories an hour. That's 50 percent more than mindless activities like watching TV. Researcher Tim Forrester, from cannyminds.com explained to the Daily Mail, "Our brains require 0.1 calories every minute simply to survive. When we do something challenging such as a puzzle or a quiz we can burn through 1.5 calories every minute."

A British Dietetic Association spokesman added, "'The brain is like any other body part -- if you are working it hard, it will need more calories to work well." There's even a book that has been written about this: "The Sudoku Diet: Creating Your Optimal Health through Logic," which claims it will help you "achieve optimal health by incorporating sudokus as part of your eating routine."

How does Twlight's Ashley Greene stay fit? She doesn't eat. At least that's what the "New Moon" star said her secret to being slim is.

The 22-year-old actress, who plays vampire Alice Cullen, said getting in shape for "The Twilight Saga: New Moon" was "really easy." She told UsMagazine.com, "We were working 12 hours a day, so it didn't leave too much time to eat."

After being nudged from her publicist following that comment, Greene added that when they did eat, it was "really healthy stuff." Apparently, she has not been sinking her teeth into her guilty pleasure: Cheez-Its.

"Cheez-Its are my vice, so I never buy them myself," she told People Magazine in an earlier interview. "I will eat a whole box. I have no self control."

Greene reported they also had a personal trainer on set, worked out four hours a day and that she practiced Pilates in the mornings. And just because filming for "New Moon" is over, that doesn't mean Greene has been slacking off.

When she's not hitting the red carpet these days, Greene is hitting the gym in preparation for the third movie in the Twilight series, "Eclipse", which is scheduled for release in 2010. "I get to fight in "Eclipse." My trainer is teaching me mixed martial arts right now. So. Cool. But I feel if I was in a real fight, I'd get my ass kicked."

Read about other "New Moon" stars and how they stay fit.

Cholesterol is a waxy, fat-like substance found in your bloodstream and your body's cells. A certain level of cholesterol is good and healthy because it is used to form cell membranes and some hormones. However, high levels of cholesterol can be unhealthy and contribute to coronary heart disease, heart attack and stroke.

People get cholesterol from two sources: the body and food. Your liver usually produces enough cholesterol on its own -- about 1,000 mg per day, which means you don't need to consume additional amounts.

Most people, however, consume additional cholesterol. Certain foods from animals, like egg yolks, meat, poultry, shellfish and whole milk and dairy products have high amounts of cholesterol. Foods from plants, like nuts, fruits, vegetables and whole grains do not have cholesterol and are recommended for those looking to lower their cholesterol levels.

The American Heart Association and the U.S. Department of Agriculture (USDA) advise limiting how much cholesterol you eat to 300 mg per day.

If you have heart disease, the limit of cholesterol per day should be 200 mg. Reducing your consumption of fatty animal products and foods containing saturated fat and trans fat will help. Be wary when purchasing food because a manufacturer can claim their food is "low cholesterol" if it contains 20 mg or less, so it's best to read all labels and eat fresh, whole foods as much as possible.

For more heart-healthy tips, test your cholesterol IQ.

Weight can be a touchy subject among friends. Honestly telling a friend whether those jeans do make her look heavy is a hard thing to do. While the number on the scale shouldn't mean a thing when it comes to close pals, the reality is some of us do change our habits, bite our tongues or plan different activities when dealing with friends who have more curves.

Click on the gallery below to take our survey and tell us how you really feel about friends and weight.

These days, it seems like we're living in a carbophobic society, where simple bread and pasta are considered as evil as butter, ice cream and Kentucky Fried Chicken. But when it comes to weight maintenance, researchers are claiming that you needn't be so wary of your wheat and potato intake. In fact, new studies show that a low-carb diet and a high-carb diet are equally effective when it comes to managing your weight a year after you've shed pounds.

Researchers at Heidelberg Repatriation Hospital in monitored 141 men and women who'd recently lost weight for year -- half were instructed to stick to a high-protein diet and the other half went on a high-carb diet. Both groups kept their fat intake below 30 percent of their total calories, and both were told to lower their saturated fat intake. The amount of weight regained over the year was the same for both groups, about four pounds, leading researchers to conclude that what matters in a weight maintenance program is overall calories, regardless of carbohydrate intake. They did notice one difference, though -- the average blood pressure went up in the high-carb group but not the high-protein group.

The moral of the story? It's not a sin to eat a plate of spaghetti every now and then as long as your diet is generally healthy. However, when it comes to carbs, try to stick to whole grains.

Be inspired by our That's Fit Success Stories. Then motivate others by submitting your own. Share how you've transformed your body through diet and exercise by sending us an e-mail at successstories [AT] thatsfit [DOT] com.

Name: Ali Shipp

Age: 29

Height: 5 feet, 6 inches

Before weight: 245

How I gained it: My mom was a single mother when I was young. She worked a lot, so it was up to my sisters and me to make our meals. There was no structure, so I never learned about portion control or how to make a balanced meal. I ate tons of pasta, potatoes and bread -- huge portions of them at almost every meal.

During the summer when I was out of school, I had the whole day to myself, and I would cook so I'd have something to do. I'd make huge breakfasts -- with potatoes and pancakes -- and then big lunches and dinners, too. I ate out of boredom and for comfort.

I rarely dieted, but I did try exercising when I got a little older. I would workout to Jane Fonda videotapes, and I'd lose maybe nine or 10 pounds. My clothes would fit a little better, but there was never lasting change. I just never had the determination to really get to it and transform myself.

Breaking Point: I became a flight flight attendant in 2004 and had the opportunity to observe a lot of different people. I began to notice differences in the way people interacted with each other. Thin people seemed like they were heard more and acknowledged. Heavier people, I noticed, had to talk louder or be very animated or boisterous to be heard. I didn't want to have to try that hard to be heard or overcompensate just because I was overweight, so I decided to make some real changes in my life.

Don't focus so hard on skinny jeans that you miss the one of the most powerful side effects of eating right and exercising -- being a happy person most of the time. You know, one of those spring-in-their-step types that genuinely loves their life, sleeps like a baby, smiles easily and is filled with boundless energy. Elizabeth Somer's new book, Eat Your Way to Happiness, reminds us the right foods coupled with exercise have a synergistic, immediate effect on your mood and cravings -- critical factors in the size of those jeans.

A registered dietitian and author of Food & Mood, Somer knows her stuff. The book includes 10 easy-to-understand diet secrets peppered with real-life success stories. If you're clueless about healthy eating, but feeling like you've got to do something to shed weight and lose your bad mood, this book is a terrific tool to educate and motivate. If you're a layman-genius in diet and fitness, Somer's assessment tools will help you identify your food and fitness areas that need tweaking.

Here's a sneak peek at a few of Somer's secrets and promises:

Kate Moss recently told WWD that her motto is, "Nothing tastes as good as skinny feels," (and then went on to say that, of course, that's impossible to follow).

Now, as someone who's interested in fashion, I think Moss is fascinating. However, as a woman who feels very strongly that women need healthy role models to look up to, I have issues with her waif look, so this statement got me fairly fired up. Whether you're aspiring to lose weight or not, it's important that you enjoy foods in a healthful way, and Moss' statement is far from showing a healthy attitude toward food.

But then, I got to thinking about her real meaning behind this. I mean, yes, Kate Moss is skinny. But her statement actually brings up a good question that applies to all of us -- are there any foods out there that you're willing to put on a little weight for?

Be inspired by our That's Fit Success Stories. Then motivate others by submitting your own. Share how you've transformed your body through diet and exercise by sending us an e-mail at successstories [AT] thatsfit [DOT] com.

Name: Kara Masucci

Age: 33

Height: 4 feet, 11 inches

Before weight: 222

How I gained it: When I was younger, I ate all the time. Food was always around, and it was yummy. I was active, and I burned it off. But I remember my mom and grandma slapping my hand when I went for the second cupcake and saying things like, "Don't eat that, you're already too big."

As an adult, I enjoyed going out to eat, and I was apathetic because I was already overweight. I just thought, "I'm already big, I might as well have the cheese fondue!" As a Nurse Practitioner, you would think I would know better, but book smarts and street smarts are different. So I resolved myself to just be happy, and I thought I was.

Breaking point: When my daughter was one year old, I started to have some health issues. When I look back at my pictures now, I see how much weight I was carrying, but at the time, I thought I looked the same as when I was a freshman in college. I was overweight, but not "obese."

Have you ever been on a Medifast diet? If you were, you might have been wearing leg warmers at the time -- this diet invention has been around since the 80s.

You won't be grocery shopping much on the Medifast diet because you're required to buy their food. Medifast diet developers say you'll lose weight fast, with a two to five pound weight loss each week on the Medifast 5 & 1 Plan. You eat often on this diet, but in very small doses. The 5 & 1 followers eat five pre-packaged Medifast meals each day, followed by one Lean & Green Meal featuring a lean protein, vegetables and condiments from their approved list of options. With 70 Medifast diet selections, you're not sucking down diet shakes all day. Food choices include chili, stew, soups, oatmeal, scrambled eggs, bars, puddings and a few other mini-meals. But forget that turkey panini with veggie chips for lunch.

Medifast is all about calorie restriction. Depending on which meals -- or, really, bars and shakes -- you choose, you're getting around 800 to 1,000 calories per day. Not much, especially if you're simultaneously inspired to clean the junk off your treadmill and start exercising.

"Someone who is generally going to use Medifast is considerably overweight to begin with and not engaged in any physical activity anyway. The recommendation is for the first two or three weeks on the diet, don't do any exercise at all," advised Constance Brown-Riggs, registered dietitian and spokesperson for the American Dietetic Association. She doesn't think Medifast can support rigorous exercise, but followers can engage in more moderate activities such as walking.

Brown-Riggs has put dozens of clients on the diet over the years with great success, noting it's a good way to jumpstart weight loss for the busy person who doesn't have time or won't take time to consider their food choices.

"It's a good way to get them started. Success breeds success, and once they're able to start losing, it's easier to transition them from Medifast to a regular eating regimen," Brown-Riggs said.

Nutritionally-speaking, meals do combine protein and carbs, so you can allegedly lose weight and retain lean muscle. They also have designed a meal plan for people with Type 2 diabetes. This diet isn't cheap, a four-week package of Medifast meals costs about $300. Comparatively, Nutrisystem costs about $350 a month, the Cookie Diet is about $240 and the high-protein Atkins diet sells a variety of a la carte bars, shakes and cuisine. The cost of the Jenny Craig diet depends on menu items ordered. Jenny Craig says their clients spend $1 more a day than the average American spends on food, but this ballpark cost remains a mystery until you start ordering.

Instead of choosing diets that require pre-packaged meals, try shopping the perimeter of the grocery store -- where the produce, lean meats and dairy are located -- and writing down all of your meals in a $5 food journal.

First there was a scale that uploads you current weight to your computer. Then there was the phenomenon of tweeting what you eat. Now technologically-savvy slimmers can take it a step further by tweeting their weight with this high-tech WiFi scale -- it automatically updates your latest weigh-in on twitter for all your followers to see. But it does more than that -- it also calculates your BMI and body fat, all for the price of $159.

I know what you're thinking: Why on earth would anyone want to post their weight on twitter? Withings, the French company behind this product, thinks that tweeting your weight will provide a you with a much-needed kick in the butt, "further motivating them by sharing their progress with followers," reported the LA Times. In other words, they want to shame you into sticking to your diet. It's a good concept in theory, but I have my doubts that this kind of 'shame' diet actually works.

What's your take? Would having your weight published on twitter motivate you or embarrass you horribly?

The Zone Diet, devised by Barry Sears, M.D., and introduced in 1995, gained popularity through celebrity dieters like Jennifer Aniston, Demi Moore and Madonna.

Like other weight-loss plans, the Zone Diet encourages dieters to cut calories, especially those from carbohydrates and unhealthy fats. It encourages people looking to lose weight to eat lots of lean meats and other foods filled with healthy omega-3 fatty acids as well as fiber-rich vegetables and fruits. To keep their blood-sugar levels stable and fend off hunger pangs, those on the plan eat five small meals a day.

Unlike some diets, the Zone Diet doesn't force people to buy certain foods, which can help cut down on the costs that sometimes accompany these plans. There are, however, a line of Zone Diet supplements. People who choose to eat them should be warned that they can be expensive.

Sounds perfect, right? Not so fast.

The diet discourages dairy consumption, which can keep those on the Zone Diet from getting several essential vitamins and minerals like Vitamin D, Vitamin E and calcium. Another common complaint is that the low-carb plan leaves dieters too tired to exercise. Coffee and soda intake can get tricky on the plan, too, because caffeine, which causes insulin levels to spike, is considered a no-no.

Others have a hard time understanding the 40 percent carbohydrates, 30 percent protein and 30 percent fat (40-30-30) ratio that Dr. Sears says will make your metabolism function best. These restrictions can be especially problematic when you're dining out. Dieters are also required to eat within one hour of waking and, roughly, every two to three hours after.

Additionally, Zone Diet creators claim -- despite a lack of evidence -- that those who follow the plan will decrease their risk of cancer, heart disease and other conditions while improving athletic performance.

If you have decided to lose weight, one of your best bets is a healthy, low-fat diet, paired with exercising several times a week. That's Fit has Diet and Weight Loss tips to help.

Read the full Zone Diet Review and Zone Diet Foods List from AOL Health.

Chromium, also called Chromium Picolinate, is a weight-loss supplement. Chromium is a naturally occurring mineral found in meat, poultry, fish and whole grains, and when combined with picolinic acid, has anecdotally been believed to help weight loss by helping in reducing body fat and increasing lean muscle. Chromium picolinate has also been linked to having positive effect on how the body processes glucose and been rumored to manage type 2 diabetes.

But while it's mostly agreed that chromium picolinate weight-loss supplements aren't generally harmful, they're not thought to carry much benefit either -- i.e. they probably won't help you lose any pounds.

According to Health Service at Columbia University, there is no evidence to prove that chromium affects weight loss.

Hank Lukaski, Research Leader at the US Department of Agriculture Human Nutrition Research Center insists, "Chromium picolinate has no effect on building muscle, reducing body fat, changing body composition, decreasing weight or increasing strength."

Officials at Harvard Medical School advocate natural chromium consumption through a healthy diet rich in whole grains, nuts, broccoli and green beans, which contain the mineral, but do not recommend chromium supplements without a doctor's consent.

What's more, Science Daily reports that there may be an increased cancer risk to those who regularly took the chromium.

Chromium picolinate supplements are taken on a daily basis before working out. Alternatively, pure chromium supplements can be ingested. Chromium and chromium picolinate supplements are available through various online dealers for approximately $10 for 250 tablets.

Trying to lose weight? AOL Health reviewed these natural weight loss aids and their claims -- to see which work and how effective they really are.

Be inspired by our That's Fit Success Stories. Then motivate others by submitting your own. Share how you've transformed your body through diet and exercise by sending us an e-mail at successstories [AT] thatsfit [DOT] com.


Name: Catherine Walker Hart

Age: 30

Height: 5 feet, 7 inches

Before weight: 168

How I gained it: Food addiction and overeating runs on one side of my family -- fast eating runs on the other side. I got both! I've always loved to eat and have always been a fast eater. Eating way past my full point was a daily occurrence in my life.

Growing up, I was very active and had a pretty decent metabolism, so I used to get away with eating too much. After I got married in 2006, I was no longer as active as I had been and my overeating started to catch up with me. My husband and I also became the "king and queen of takeout." When you eat most of your meals from restaurants, you don't have control of what goes into them, and the portions are larger than one person needs. I also was a bit of a carb addict, easily eating four to five times the appropriate amount of carbs in my meals. My husband and I also developed an ice cream habit. We could go through an entire pint on a nightly basis.

The more weight I put on, the more uncomfortable I felt, which only led to more overeating. And I was not burning off any of it! I tried several attempts at the gym, but I always felt lethargic and unmotivated. Eventually, I gave up.

Breaking Point: I started to notice that I could no longer cleverly hide my weight gain with baggier clothes. I have a small frame, so there was a window of time when I could hide extra pounds, but I was gaining weight beyond that window. The depression about my weight really kicked in when I had to buy a new pair of jeans in a larger size for the third time.

I became incredibly self-conscious about my weight and felt very uncomfortable in my own skin. I liked to think of myself as a strong, active person, and there I was carrying around an extra 35 pounds. I felt like I wasn't myself.

My weight was increasing, and I wasn't having any success changing to a healthier diet. In fact, I don't think I even understood what it meant to eat healthier. My grandfather had been a lean, strong, active athlete his entire life, but his addictive eating cut his life short. I knew in my heart that I had his genes and that if I didn't change my lifestyle now, I could be on the road to obesity with serious health consequences. I needed to kick it in the butt! I decided right then and there that "being heavy" was just a phase: I would not be a heavy person for the rest of my life.

The Mayo Clinic Diet is a fad diet purported to help people lose 50 to 55 pounds during a 10-week span. It has no connection to the respected Mayo Clinic, a top research hospital, in Minnesota.

The basic premise of the diet is that dieters should ban all complex carbohydrates, but can eat as much protein and fat as they want. One of the "rules" of the diet even states, "At any meal you may eat until you are full -- until you can't eat any more."

Experts agree that a diet based on unbalanced nutrition and limited food choices, like the one recommended in the Mayo Clinic Diet, can be unhealthy. Plus, the boredom associated with eating the same foods over and over can prompt a return to old eating habits once someone goes off the diet.

The quick weight loss associated with the plan is also unhealthy. A better option than the Mayo Clinic Diet is the Mayo Clinic Healthy Weight Pyramid, a lifestyle plan that includes a variety of healthy foods and daily exercise -- and is actually associated with the Mayo Clinic. It offers personalized menus, shopping lists, meal plans, results charts and dining-out tips.

Learn more about diet hoaxes that can sabotage your weight loss plans and check out That's Fit's Fitness page for tips to get in shape.