Original post by ch0c0h01icAll diets work in one of two ways:
1) Calorie restriction
2) Increased activity level
Most people consume large amounts of carbohydrates, reducing carbohydrate consumption reduces your calorific intake and in doing so creates a calorie deficit, which causes you to lose weight - it is no more mystical than that. The "metabolic" benefit that some people speak of is negligible if not non-existent. Equal or better results could be gained by a simple calorie controlled diet.
Low carb and ketogenic diets have a couple of fundamental problems though:
1) Carbohydrates are the preferred fuel source of the brain and your muscles - restrict carbohydrates and you will see a fall in athletic performance, lethargy, lack of concentration, headaches, mood swings, etc. Sure some people see an improvement after a couple of weeks but a lot don't without eating more carbs or limiting exercise intensity and volume. Again far from ideal.
2) Malnourishment - most people's diets are deficient in fruit and vegetables, low carb and ketogenic diets take things even further by restricting fruit and vegetable choices and consumption even more. To match this some people use vitamin and mineral supplements but they're expensive and have questionable efficacy.
3) Compliance - low or no carb diets are highly restrictive and do not fit in well with day to day life. The result is that most people give up within a relatively short space of time and regain most (if not all) of the weight they lost.
4) Cost - large amounts of high quality meats and fish are expensive. Few people can afford to maintain it or do it properly.
5) Health - low carb and ketogenic diets are deficient in vegetables and fruit, and within that fibre, vitamins and minerals, and a lot of people trying to cut the cost of the diet also eat more processed meats. Again, far from ideal.
Fat's aren't very satiating. Protein, fibre and water rich foods - YES. Fat - NO. If you're getting the majority of your calories from fat it is relatively easy to overeat or even gain weight.
Considering low carb and ketogenic diets are low in fibre and water rich foods (eg; vegetables, beans, lentils) it isn't ideal.
More myth than true.
It is harder than a lot of people think to lose large amounts of muscle, by and large we're talking about chronic malnourishment coupled with a significant calorie deficit and a lack of resistance training full stop.
The reason why rapid weight loss isn't ideal is because you're sacrificing your health and performance, and in the short term the majority of your weight loss is going to be water, not fat or muscle.
Paleo is a fad diet? Maybe not but it scores highly in the dogma stakes.
Sure it is a step forward for most but do we know that it is what Paleolithic man ate? Do we know that we are "designed" to eat it? Do we know that it is the "best" diet? No.
Even Paleo proponents can't decide amongst themselves - some say dairy products are ok, some not, some say legumes are ok, some not, some say rice is ok, some not, some say nuts and seeds are ok, some not, etc. All of that is woven together with a mixture of irrationality and poor science. For example, some foods are excluded from the diet because they contain "antinutritional factors" whereas in other instances it is ignored. Studies which found genetic markers to gluten sensitivity in some diseased populations are presented in a way to convince the reader that gluten CAUSED these diseases when in actual fact there is little or no evidence that that is the case. Elsewhere conflicting studies and evidence is ignored in an attempt to make a more convincing argument.
Frankly it is a mess.