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.)
If you want to lose fat, you have to eat fat...the right kind, that is. Adding healthy fats, in the form of monounsaturated and polyunsaturated fats, can help you feel more satisfied with your meals. Yasi Ansari, MS, RD, CSSD, national medial spokesperson for the Academy of Nutrition and Dietetics, says, "Fat sources that I recommend boosting in the diet come from unsaturated fatty acids found in foods like olive oil, nuts, avocados, fatty fish, and eggs, as they can help increase satiety while providing a variety of health benefits when consumed in moderation." You can increase your intake of healthy fats by adding some chopped avocado into your salads, enjoying wild salmon twice a week, and having a little peanut butter with your post-workout snack or smoothie. Just remember to enjoy them in moderation as they're still very calorie-dense, Ansari says.
"Research continues to support the role of a high-protein diet and weight loss, however, we don't want to reach those protein needs exclusively with animal proteins. Plant proteins found in beans not only help us feel full and stabilize blood sugar but beans are associated with longevity. Who cares about being skinny if you die young?" —Jennifer McDaniel, MS, RDN, CSSD, LD, food and nutrition expert

Make sure that the diet has been studied extensively for safety — and discuss any changes with your physician or registered dietitian before beginning a new diet. (If you don’t have a dietitian, find one in your area at the Academy of Nutrition and Dietetics website.) And do a self-check to ensure the diet fits with your own values and preferences.
"Use a VersaClimber or take a VersaClimber class. These machines are still not that common, but in my opinion they are far more effective for weight loss than other forms of cardio. They require you to use a large portion of your muscles and it's functionally better for you than other forms of cardio like spinning. Everyone is talking about Rise Nation in LA at the moment as they are the first dedicated VersaClimbing studio. There's no harder cardio workout I have tried. To lose fat you have to put in the work. — Dan Roberts, celebrity trainer and creator of Methodology X
"If weight loss is the goal, I recommend learning how to properly deadlift. Deadlifting recruits more muscle fiber at once than any other exercise. More muscle working equates to more blood flow, an increased heart rate, more metabolic demand and output. It's compound, multi-joint and more bang for your buck, not to mention you'll develop an excellent posterior from them." — Victoria Viola, PN Certified Nutrition Coach, NSCA CPT, Co-Founder, Excelerate Wellness, LLC

Consequently, researchers have widely discredited the hCG diet, which involves using hCG injections, pellets, sprays, or drops, and consuming  as few as 500 calories daily. The diet is problematic not only because there’s a lack of research on hCG supplements, but also because the calorie requirement is dangerously low, potentially leading to nutrient deficiencies, fatigue, hormone imbalances, blood clots, and other issues. Thus, most experts agree the hCG diet is not safe for anyone, the Mayo Clinic notes. (35)

Based on the concept of caloric density, which states that some foods have few calories in proportion to their size (say, a lettuce), while others have lots of calories packed in small portions (a regular chocolate chip cookie comes to mind), Volumetrics divides foods into 4 categories based on their calorie/volume ratio, and is perfect for people looking to binge on some foods while still shedding pounds. However, as with the calorie counting approach, Volumetrics does not take into account the quality of the calories, prioritizing quantity instead. The app Noom and Weight Watchers (both reviewed above) share similarities with this diet theory.
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