A Systematic Review of Evidence on the Use of Very Low Calorie Diets in People with Diabetes

Michael's and Dr. Eades's comments together raise what I consider the obvious issue with these VLCD's. Ok, so they work to put diabetes in remission. Do they do so because they reduce calories significantly or because they also restrict dramatically the consumption of the macronutrients that make up total calories? So maybe they work because they restrict protein or fat or carbohydrate consumption? The latter, or maybe the latter two, would be my guess.  (I have a one-track mind.) 

A 300 kcal/day VLCD is going to be at most 150 kcal/day of carbs, which means borderline ketogenic. A protein sparing modified fast of the kind the Eades used, as Mary Dan noted, is ketogenic. As designed originally by Bistrian and Blackburn it was 600 to 800 kcal/day of only meat, fish or fowl. Hence, the only carbohydrates came from the glycogen in these foods, maybe five percent of the calories. Protein content was high as a proportion of calories but very low in absolute terms. 

One way to test whether the benefits of the VLCD were from the calorie reduction or the carbohydrates would be to fix the carbohydrate at that of the VLCD and then add fat back to increase the calories -- i.e., do what the Eades did. Or what Virta Health has been doing. The fact that the benefits seem to be identical suggests that it's the carbs not the calories. And now you have a relatively high-calorie ketogenic diet which is not only way more fun than starvation (whether or not it's way more fun than eating donuts and drinking beer), and way more sustainable. Perhaps even way healthier. 

In a functional science, the researchers would be asking these kinds of questions: now that we've observed a benefit from these very low-calorie diets, what's the mechanism?  What are reasonable explanations and can any of them be ruled out by this data? 

In our clinic, back in the late 80s and early 90s, we used a VLCD frequently as a tool to help overweight, often diabetic or borderline diabetic patients lose weight and regain metabolic control. The variant we used was a PSMF (protein-sparing modified fast) involving consuming several protein shakes each day, restricted in carbohydrate and fat, coupled with a single (what would now be called 'keto') meal. 

Initially we used a regimen of only the protein/low carb shakes and no 'solid' food (similar to what Oprah famously did on the Optifast program). It works very well as any VLCD will work very well, almost no matter what its composition. When calories are that low, it just about doesn't matter what they're made of as the body will use every single one of them and the metabolism will heal. (Granted, as this review points out, the numbers are almost always significantly better if the content is adequate in protein and restricted in carb). 

So, just shakes works well and is very simple and straightforward for patients to use, if very boring. And it's a helpful tool for those patients (and there are quite a few) who have a fraught relationship with food; for them it removes the risk of error on what to eat and how much. One drawback, though, is cost, not that the shakes themselves are expensive, but rather since formula diets, such as an 800 VLCD, require some ongoing medical supervision for safety.

But after working with a lot of patients on this kind of regimen, we quickly came to see that the lion's share of the benefits of the PSMF on weight reduction and metabolic healing could still be had with the addition of a single tasty, savory meal providing protein and fat, with reduced carb to accompany the shakes. The meal content was pretty much like what CrossFitters are familiar with: meat, vegetables, nuts and seeds, some fruit, little starch and no sugar. And adding it bumps up the calories to something more like 1200 or maybe 1500 a day and makes the regimen much safer and easier to stay with longer term. 

Plus the addition of fat in the meal encourages the gall bladder to work daily and sharply reduces the chance of stone formation that is a risk on any long-term very low fat diet. 

Mike wrote his first book, called Thin So Fast, in 1989 about how to safely undertake a PSMF + meal plan on your own and put the tool into the hands of people outside a rigorous hospital or clinical setting. That book was, interestingly enough, the first time so far as we've been able to determine that the phenomenon of 'insulin resistance' was introduced to the lay public. 

A VLCD is a tool, like any diet is a tool, used to tackle a task at hand. And it works well. (But then so does whole food keto, and as Michael Thalmann succinctly commented, that's waaayy more fun!)

Yeah, but keto is waaayy more fun than starvation 🤪