The studies I mentioned before show that a number of the diets work, the high carbohydrate and very low-fat diets whole food plant based like the Ornish diet, or the high protein and low carbohydrate diets like the paleo, or the high fat and low carb diets like the ketogenic diet. The truth is, they all work.
Now I appreciate that some people’s food choices are not just about their weight, but also about their overall health and environmental or ethically based choices, which is great. So you decide based on your personal preferences what is best, and work with a therapist to review this. Hopefully, this info gives you support no matter what you choose.
One study called the POUNDS LOST (Preventing Overweight Using Novel Dietary Strategies), a two-year trial comparing different weight loss strategies, found that healthy diets that varied in the proportions of carbohydrates, protein and fats worked equally well in the long run and that there was no speed advantage for one diet over another.
However, there is some evidence that a low-carbohydrate diet may help people lose weight more quickly than a low-fat diet. The DIRECT study compared low-carb, low-fat, and Mediterranean-style diets and found that after 2 years, weight loss and maintenance were better for low-carb and Mediterranean style diets as compared to low-fat diets.
The A to Z weight loss study showed that after 12 months the low carb diets lost 2-2.5kg or about 5 lbs more than the low-fat diets.
So it seems quite clear that whilst some diets may have an edge like the low-carb diets, there are roughly similar and the common ground is healthy food and less of it.
But remember it is not just about weight, it is also about other factors like improving blood pressure, cholesterol and blood sugars etc. A 2012 meta-analysis study with 2780 people found that both low carb and low-fat diets reduced blood pressure, blood sugar and cholesterol, roughly equally. With perhaps a slight advantage to the low carbohydrate diet for cholesterol.
A key point though is – what do you replace the carbohydrate with? You can replace them with more vegetables, nuts, seeds, herbs and spices, healthy fats, or you could replace them with lots of meat, refined fats and processed food like protein bars. A prospective cohort study of over 82,000 US nurses reported that a low-carb diet that replaced the carbs with vegetables, plant proteins and healthy unsaturated fat was associated with a lower risk of coronary heart disease and all-cause death over 19 years of follow-up in both men and women. In contrast, a low-carbohydrate diet emphasizing animal sources of fat and protein was associated with a higher risk of type 2 diabetes mellitus and all-cause mortality. So whilst it matters what you take out, it also matters what you replace it with.
So in conclusion, both low fat and low carb work to a degree but low carb seems to have an edge if you replace those carbs with a healthy vegetable, fat or protein. If you think a low carb diet is for you – that basically means reducing, not necessarily excluding, just reducing the foods you eat like refined grains, rice, pasta, wheat, bread, cereals, potatoes and corn and replace them with vegetables, herbs, spices, nuts, seeds, healthy choices for fat like mono- and polyunsaturated fats like olive oil, avocado, and healthier protein sources like fish, nuts, legumes, beans and poultry.
The main problem with strict low carb diets is compliance. It can be hard to stick to as it is quite restrictive and some people, if they are too strict, run the risk of certain nutrient deficiencies. I will discuss this later in the video on the ketogenic diet.
Generally for both strict low fat and low carb diets long term adherence is the key. A meta-analysis of 27 studies in 2016 showed that the overall adherence rate was only 60% for ~12 months. Another more positive study in 2009 showed that the average adherence was ~85% for the Mediterranean diet versus 78% for the low carbohydrate diet.
Hence next we shall discuss the Mediterranean diet which is the diet with the most evidence behind it and one of the easiest to stick to.