Dietitians are rolling out their ritualistic warnings about 'fad diets', so it must be January. Prepare to be warned about the dangers of avoiding gluten, quitting sugar or going Paleo.
According to many dietitians, crazy 'fads' such as quitting sugar are dangerous because they ask us to 'cut out whole food groups.' Only a dietitian high on sugar would describe sugar as a 'food group', but I guess the argument could apply to the stricter forms of Paleo eating which ask devotees to ditch dairy, legumes and grains.
If food group deletion is the reason for official opposition to paleo, gluten free and quitting sugar, why are they quite happy to give a free pass to vegetarianism and its more extreme cousin, veganism? Both of these diets do actually cut out food groups and both require careful management in order to avoid significant nutrient deficiencies. But they are rarely attacked by dietitians.
Vegetarian diets do not contain meat, poultry or fish. Vegan diets go a little further and also exclude dairy products and eggs. Both diets have been part of British and US culture since the mid-19 century, so we've had a bit of time to study them in the wild.
Research indicates that "the health of Western vegetarians is good and similar to that of comparable non-vegetarians". However, studies also tell us that while vegetarian diets provide higher amounts of carbohydrates, omega-6 polyunsaturated fats, fibre, vitamin C, vitamin E and magnesium (compared to omnivores) they have lower amounts of protein, saturated fat, omega-3 fats, vitamins A, D and B12 and Zinc. Vegans are usually particularly low in B12 and also Calcium, a deficiency they are likely to share with hard-core paleo enthusiasts because both avoid dairy.
We use vitamin B12 to create our DNA, red blood cells and the myelin insulation around our nerves. Not having enough of it can result in fatigue, weakness, psychiatric problems and anaemia. B12 deficiency in children and the elderly is even more worrying. Studies have consistently shown that children and older people lacking B12 suffer significant cognitive defects such as memory and reasoning. The lack of long chain omega-3 fats, the abundance of omega-6 fats and deficiencies in the fat soluble vitamins A and D are also serious cause for concern particularly in pregnancy.
Of course, omnivores can also have nutritional deficiencies if they don't follow a balanced diet. And this does not mean that vegetarian or vegan diets should not be followed, just that they need to be carefully managed, particularly in pregnant women, children or the elderly. But that is what you might expect from a diet that actually does delete 'whole food groups'.
Humans are omnivores. This does not mean we can't choose to delete whole food groups. But it does mean that when we do that, we need to be very careful to ensure we are still getting all the nutrients we need.
So the next time you hear a dietician banging on about 'fad diets' remember two things. First, sugar is not a food group and you may safely remove it forever (and do yourself a significant favour). Second, the biggest offender on the 'delete whole food group' front is the one they dare not mention -- vegetarianism.