Rather than rely entirely on the information provided by the companies to determine weight management effectiveness, we spent weeks browsing through hundreds of unpaid customer testimonies (not endorsed by any company) to get a feeling on the accuracy of the claims they make. In fact, these testimonials provided us with a much more truthful and in-depth insight regarding how effective diet plans really are. 
Contrary to other low-carb approaches, the South Beach Diet makes a clear distinction between “good” and “bad” fats (avocado oil is good, butter is bad), and only prohibits the consumption of certain, but not all, carbs. This means that, while the South Beach Diet has certain similarities with the keto approach, is not strictly ketogenic, but rather keto-friendly.
The best low-cal diet plan isn't a diet so much as it is a method. CICO stands for "calories in, calories out" and is based on the mathematically sensible principle that as long as you're burning more calories than you're eating, you'll lose weight. All you need to get started is a way to track your calories—there are plenty of apps on the market although a pen and paper works great too—and a food scale to keep you honest about your portion sizes. (Also read this guide on how to safely cut calories to lose weight.) People love the simplicity and straightforwardness of the plan. And while it may not be the fastest way to lose weight, you're guaranteed to have success long term. (Just know that some weight-loss experts actually don't recommend calorie counting.)
"Anytime you’re stressed, you probably go for food," Dr. Seltzer says. (Have we met?!) That’s because cortisol, the stress hormone, stokes your appetite for sugary, fatty foods. No wonder it’s associated with higher body weight, according to a 2007 Obesity study that quantified chronic stress exposure by looking at cortisol concentrations in more than 2,000 adults’ hair.

This diet theory, consisting of 10% or less of daily calories from fat, is the flip-side to Atkins, Keto, and Paleo. Proponents of the ultra-low-fat approach adhere to a diet rich in plant foods, low in animal products, and high in carbohydrates (80% or more of daily caloric intake). An example of this type of theory is the TLC (Therapeutic Lifestyle Changes) Diet created by the National Heart, Lung, and Blood Association with the purpose of helping people combat heart disease, lower cholesterol levels, and prevent digestive problems.
This may explain why the fat-burning effects of eating more protein were confirmed in a study published in the American Journal of Physiology. One group was fed a high-protein diet (just over 1 gram per pound of body weight per day) while the second group consumed an amount closer to the lower recommendation of the RDA (recommended dietary allowance). The group eating the higher-protein diet burned the most fat.
Everyone’s body is different when it comes to digesting some gas-forming foods, but there are a few you should be wary of: It’s best to avoid beans and cruciferous veggies (think cabbage, Brussels sprouts, cauliflower, and broccoli) for a couple of days if you want to look slimmer. Choose lean proteins like chicken and fish or, if you’re vegetarian, go for small amounts of nuts and seeds for protein. Pair with non-gassy vegetables like asparagus, spinach, and cucumber to help prevent bloat.
Because of its focus on frequent meals, portion control, mindful eating, proper hydration, and exercise, the company claims (and some studies show) you’ll lose between 8 to 13 pounds in the first phase, and an average of 1 to 2 pounds per week. After reading client testimonies posted on the web, we feel these numbers to be fairly accurate of South Beach Diet’s effectiveness.
Forget old low-carb diet plans that focused on processed protein bars and shakes. This year, the keto diet got high marks for low carb. Keto, short for "ketogenic," is all about training the body to burn fat for fuel. How? By eating fat—and lots of it. Most keto diets recommend getting at least 70 percent of your daily calories from fat and the rest from protein. The goal is to eat as few carbohydrates as possible. Proponents say it helps them drop weight fast with little or no hunger in addition to perks like more energy and mental clarity. (Interested? Here's everything you need to know about the keto diet.)
Protein is also important for preserving muscle mass as you lose weight. If you cut back dramatically on calories and drop weight too fast, your muscles can suffer. Your body starts pulling from lean tissue like muscles and organs to fuel itself, and your metabolism slows to conserve energy. That’s why super restrictive diets that have you dropping weight fast aren’t healthy over the long run.
"People should pick activities they enjoy and that fit into their lifestyle in order to increase their chances of sticking with it to lose the last 10 pounds. For those who have hit a weight-loss plateau and can't seem to lose that weight, you'll need to mix things up in order to see results. Tabata-style training, HIIT classes and resistance training can all be effective weight-loss modalities for the right person." — Timothy Lyman, ACE certified personal trainer and Director of Training Programs at Fleet Feet Pittsburgh

"Your body begins to work differently. This study proves that small amounts of nourishment throughout the day are better than the same amount of food concentrated in three big sittings. If we feed the body at regular intervals we send a signal to the body that it doesn't have to store calories. Conversely, when we skip meals we send just the opposite signal for the body to store calories, creating a negative effect on the metabolism." — Dr. Wayne Scott Andersen, co-founder and Medical Director at Take Shape For Life 
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