To fully understand the medical value of nutrient- complete formulated foods as a tool for weight management, there are a few fundamental concepts that need to be explained. These include the protein sparing modified fast; the mechanisms and value of ketogenic diets, minimum safe energy intakes and enteral food formulas. The value of this approach is amply demonstrated by substantial clinical evidence accumulated over a period of nearly 40 years.
Beginning in 1975, a series of reports from the Bistrian and Blackburn medical team demonstrated the value of a very low-energy dietary regime for weight management in a variety of difficult obese patients. This team had the advantage of considerable nutrition expertise and they devised a protein sparing modified fast — essentially a home-concocted Very Low Calorie Dietary formulation that was nutrient complete. Unfortunately the remarkable success (and safety) of this approach was obscured by commercial greed – not by the medical team, but by external commercial exploitation. A commercial product was developed and widely sold that contained virtually no nutrition. it was based upon a hydrolyzed nutritionally incomplete protein (collagen) in cherry syrup. This product was heavily promoted and widely hyped and inevitably, it resulted in a number of deaths.
Quite properly, the Liquid Protein Diets have not been available since the late 1970s. Unfortunately however, a total lack of nutritional understanding led to the assumption that low energy liquid formulations were dangerous as a concept. In fact there are now nearly 40 years of worldwide experience with numerous properly formulated nutritionally complete products which should be evidence enough of safety.
There is an often stated mantra, surprisingly even from nutrition specialists, that there must be some level of calorie intake (in the neighbourhood or 1000 to 1200 calories per day) below which diets become unsafe. Once again, it is simply the superficial understanding of food and nutrition biochemistry that has given this notion some credence. All common foods may be thought of basically as recycled nutrients from the plants and animals we choose to consume. All are complex formulations of the chemicals that make up the composition of those plants and animals. Many of these chemicals are common to all living things and some of them are useful and even necessary for human health. They also contain large numbers of chemicals that are either inert or toxic to other animals, including humans. The key point, however, is that there is no naturally occurring food that contributes all the required nutrients for humans. We therefore require a varied diet to attempt to create a mix that will maximize the chemistry we need and minimise the problematic substances.
The crucial point here is that – given the varying chemistry of the plants and animals we consume — it is virtually impossible to assemble a nutrient-complete daily diet with a total of less than around 1200 calories. When food diets with lower calorie intakes are provided, nutrient deficiencies invariably cause illness. It is very important to note here that it is the nutrient deficiencies — and not the low calorie count — that causes the problems.
When it became clear that nutrient complete enteral feeds could be provided that contained, by design, all the essential nutrients, it demonstrated that the minimum calorie intake was nowhere near the 1200 calorie barrier. In fact, modern formulations have a calorie component determined primarily by the calorie contribution of the essential amino acids and essential fatty acids (and to a lesser extent by the lactose from the necessary milk component, which provides very high quality proteins to the formulations). These limits however are closer to 400 calories per day, not 1200.
The most effective and safe formulations are those that induce ketosis. Ketones are a by-product of the incomplete breakdown of free fatty acids. They are essential for sparing protein utilization and helpful in controlling the hormonal balance between insulin and giucagon, which helps control hunger. Many of the body’s tissues can use free fatty acids as fuel, but critically there are a few (including the brain) that cannot. Unless there are sufficient ketones present, which are water soluble and can pass through the blood brain barrier to provide energy for brain function and survival, the body must de-aminate amino acids from proteins to create glucose. Glucose can not be created from fat. This is why ketones are protein sparing. Virtually all tissues, with the possible exception of liver, can use ketones for energy.
It is clear from the controlled accessibility of very low energy diets through healthcare professionals, that detailed records are available of the successful results of this form of treatment. A large number of these results have been published. Proper nutrition, provided in defined very low calorie formulations, results in maximum safe rates of weight loss and there is considerable evidence to support its value to modern medicine.
S.N Kreitzman Ph.D, R.Nutr. (UK Registered Nutritionist)
V. Beeson Howard Foundation Research Ltd.

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