You may lose weight on the Paleo Diet. If you build a “calorie deficit” into your Paleo plan – eating fewer calories than your daily recommended max or burning off extra by exercising – you should shed some pounds. How quickly and whether you keep them off is up to you. A 2015 review in the Journal of Gastrointestinal Liver Diseases concluded that a Paleo-esque diet “might be an acceptable antidote to the unhealthy Western diet, but only unequivocal results from randomized controlled trials or meta-analyses will support this hypothesis.” On that, we’re still waiting. In the meantime, here’s what has been found about the diet and others like it:
Whole30 is a nutritional program designed to change the way you feel and eat in 30 days. Basically, you have to remove all of the potentially inflammatory foods and beverages in your diet (think: added sugar and sweeteners, alcohol, grains, legumes, dairy, processed foods and beverages, baked goods, and junk foods) and eat three "clean" meals a day, made with Whole30-approved ingredients (think: meats, seafood, veggies, and eggs).
You may notice that the following meal plans do not include any snacks. This is because, technically, snacking isn’t really something you should do while on a Whole30. Just be sure you’re getting enough food at each meal (which may be hard at first as you adjust to eating whole, real food and no processed “foods”) and you won’t need to snack. If you do feel the need to eat something between meals, try to keep some cut-up veggies on hand so you’ve got something easy and quick nearby and aren’t tempted to grab something non-Whole30.
There are about half a dozen diets that are very similar. They all recommend you eat "meat and veg" The reason Whole 30 works for me is because you can have potatoes and fruit. An example of a whole 30 meal would be: 2 pork chops, mashed potatoes made with chicken stock, green beans, finish with your choice of fruit. My favorite is a few grapes or pineapple chunks. Also the goal it to make it 30 days without cheating. There have been several times I would think: OK I can't cheat now I only have __ more days to go. Having an end in site helped me. When I started adding back in food groups after the 30 days. I figured out that I do not do well with Dairy. Now the only dairy I use is real butter. I never thought I could live without cheese... But now I don't think it's a good idea for me. So it helps you figure out what you can and can not eat and still feel good.
With a very simple shift we not only remove the foods that are at odds with our health (grains, legumes, and dairy) but we also increase our intake of vitamins, minerals, and antioxidants. Here is a great paper from Professor Loren Cordain exploring how to build a modern Paleo diet: The nutritional characteristics of a contemporary diet based upon Paleolithic food groups. This paper also offers significant insight as to the amounts and ratios of protein, carbohydrate and fat in the ancestral diet.
Level One (CF-L1) is the introduction level, where participants attend a group weekend class, talk about the basic methodology and fundamentals of CrossFit, and learn how to conduct their own classes. They go over techniques and how to adjust them for those who cannot perform them. After completing the Level One training course, one should be confident in conducting a class, scale workouts accordingly for athletes, and hold CrossFit to its standards. In the second level, training goes deeper into the mechanics of the movements and how to be leaders and communicate with other students. In the Level Two course, participants learn about athletic capacity and are evaluated as a trainer in groups. In order to earn the Level Three certificate, a coach one must complete 1,500 hours of active fitness coaching and become CPR certified. To earn the Level Four certificate, the highest level currently recognized by CrossFit, Inc., the coach must record several years as a Level Three and pass a test.
Cordain explains that high intake of fruits and vegetables is one of best ways to reduce chances of cancer and heart disease. He notes that protein has twice the calorie burning effect of fat and carbs and is more satiating than both. He explains that starch, fats, sugars, and salts together cause us to keep eating. So if we limit our diet to fruits and vegetables and/or meat, we’ll stop eating when we’re full. And if you stop eating when you’re full, you’ll lose weight and won’t get fat. And as you lose weight, your cholesterol will improve (regardless of what you eat). This all makes sense and can’t really be disputed. If you want to lose weight, the Paleo diet will get you there and probably quickly. But Cordain’s hypothesis applied to long-term health falls short.
Excluding foods. The exclusion of entire categories of commonly eaten foods like whole grains and dairy requires frequent label reading in the supermarket and in restaurants. It may also increase the risk of deficiencies such as calcium, vitamin D, and B vitamins, if these nutrients are not consistently eaten from the allowed foods or a vitamin supplement. For example, there are some nondairy calcium-rich foods that are absorbed well by the body such as collard and turnip greens or canned bone-in sardines and salmon, but you would have to eat five or more servings of these greens and fish bones daily to meet recommended calcium needs. (Note that some greens like spinach that are touted to be calcium-rich also contain oxalates and phytates that bind to calcium so very little is actually absorbed.) One small, short-term intervention study of healthy participants showed a 53% decrease from baseline in calcium intake after following a Paleo diet for three weeks.  Furthermore, the exclusion of whole grains can result in reduced consumption of beneficial nutrients such as fiber and thus may increase one’s risk for diabetes and heart disease.
Both feeling hungry all the time and never feeling hungry are common on the Whole30 diet, especially during the first two weeks as your body adjusts to new sources of energy. Eventually, though, you shouldn’t feel those pangs since protein and fiber are filling, and you’ll get plenty of both. Plus, you’re allowed to eat as much as you want and add Whole30-compliant snacks to your meal plan, provided you truly are hungry. One small study of 29 participants published in Nutrition and Metabolism in 2010 found Paleo eaters (who have relatively similar diets to Whole30 followers) felt just as full but consumed fewer calories than their Mediterranean counterparts.
CrossFit programming is decentralized, but its general methodology is used by thousands of private affiliated gyms, fire departments, law-enforcement agencies, and military organizations, including the Royal Danish Life Guards, as well as by some U.S. and Canadian high-school physical-education teachers, high-school and college sports teams, and the Miami Marlins.