There is a clinical problem of obesity, type-2 diabetes and cardiovascular disease. And there is controversy about whether or not total calories matter or if there is something to the composition of calories as in a high-fat, high-protein, low carb diet.
The minimal amount of daily carbohydrate recommended is 130 grams per day (ADA; IOM). The IOM says healthy eating is carbs 45-60 percent carbs.
As a summary of HPLC diets, there are many:
Dr. Mechanick has an interest in Paleo dieting since it is based on genomic programming and evolutionary biology. Like McKeown before him, he says that Mediterranean diet is no single diet, but is characterized by a diet high in fruits and vegetables, moderate fish and alcohol, high in olive oil, high in polyphenols and little meat. The cardiovascular benefits have been demonstrated.
What's the theoretical advantage of HPLC diets? They restrict refined carbohydrates, lower glycemic excursions, insulin levels, total calorie intake. High protein may increase satiety.
But there are concerns there's evidence for lack of long-term benefit, increased risk for kidney stones, ketosis and bad breath, low in fiber, calcium, magnesium, potassium, iron, folate, thiamine; is higher in saturated fat then increase in CVD risk, increase cancer risk if low in fruits and vegetables.
What's the compromise? To tailor a HPLC where carbohydrate is replaced with healthy fats like MUFAs, PUFAS and omega-3s along with high biological value proteins, especially plant proteins, low-glycemic complex carbs.
Dr. Mechanick then goes into quite a few of the studies regarding low-carb diets and comparisons to other diets. I'm going to try to summarize by saying that: According to studies and meta-analyses on RCTs, a Mediterranean-style low-carb diet leads to same weight loss and is healthier than other low-carb diets.
However, Dr. Mechanick notes, the data do not support that all people should be on low-carb diets.
He concludes that there are inconclusive results of HPLC diets based on well-conducted PRCTs, there are inconsistencies due to problems with surrogate markers, and that we need a systems approach to better understand complexities.