450-700kcal/day Diet Cuts 7% Body Fat in 3 Weeks - Only if You go Keto, Though, it Will also Increase Lean Mass by 4%

Not basing both the ketogenic and regular very low calorie diet on whole foods, only was only one of at least 3 problems with the study at hand that can thus not be considered the ultimate litmus test to compare VLCD with en vogue VLCKD diets.

Ketogenic diets are characterized by constantly low insulin levels. That's not exactly what has been considered muscle protective in the old age of bodybuilding, where insulin's protein-anabolic and anti-catabolic effects were still hailed as a benefit you wouldn't want to miss (Fulks. 1975; Woolfson. 1979), but according to a recent study from Rome, a ketogenic diet may be the go-to diet for everyone trying to shed as much as weight as possible in as little time as possible by cutting your total daily energy intake down to a hilarious <700 kcal/day (Metta. 2016).

Now, cutting calories back that much may sound (and be) idiotic for someone who has been lean all his / her life and is just trying to make his abs more visible. For someone whose overweight is threatening his life, it may be a life saver...

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It can be a life-saver that backfires if you end up losing the already low amount of metabolic currency (=skeletal muscle) that has remained unused under a thick layer of body fat for years, though. To avoid that from happening Metta et al. (2016) randomized twenty-five healthy subjects (18 and 65 years, with a BMI ≥ 25 kg/m², percentage of body fat (PBF) ≥ 25 for male, and ≥ 30 for female) randomly (R) divided into two groups (X and Y). The group X received the VLCKD, and the group Y received the VLCD - both for 3 weeks over which 3 subjects dropped out:

• The very-low-carbohydrate ketogenic diet (VLCKD) aimed at an energy intake of 450-500 kcal per day for female and 650-700 kcal per day for male, with 35-40% of calories from fat, < 10% of calories from saturated fat, 5% of calories from carbohydrates (< 6 g), and 55-60% of calories from protein, corresponding to 1.2 g (female) or 1.5 g (male) / kg of body weight, and an intake of 25 mg of fiber per day. The half of the amount of daily protein was reached using aminoacid supplement, called Amin 21K (Italfarmacia, Rome, Italy | product website). The powder of aminoacid was dissolved in water and drunk at the breakfast and lunch or dinner.
• The very low restricted-calorie diet (VLCD) aimed at an energy intake of 450-500 kcal per day for female and 650-700 kcal per day for male, with 35-40% of calories from fat, < 10% of calories from saturated fat, 15-20% of calories from carbohydrates (< 20 g (female) or < 30 g (male), and 45-50% of calories from protein, corresponding to 0.9 g (female) or 1.1 g (male) / kg of body weight, and an intake of 25 mg of fiber per day.

In both groups, a capsule of multivitamin, proper integration of mineral salts and an alkalizing product were prescribed. The correct administration of diet was evaluated by urinary keto-stick. The study was conducted in double-blind fashion and the subjects were asked not to change their lifestyle habits.

Figure 1: Changes in body composition over the 3-week study (N=18 subjects remained | Metta. 2016).

In view of the identical energy and protein intakes (45-50% of calories), the DXA-based body composition data in Figure 1 is unquestionably impressive, as it seems to support the notion that cutting out carbs from a nutritionally clearly deficient diet was enough to turn a hunger diet into a muscle-preserving fat burning wonder diet, but...

1. on a per/kg basis the protein intakes were everything but identical - with 0.9g/kg in the female and 1.1g/kg in the male study participants of the normal carbohydrate (VLCD) arm of the study, the ketogenic (VLCKD) diet provided 33% and 36% more protein for the female and male study participants, respectively;
2. the subjects in the VLCKD group got sign. amounts of protein from a whey + extra-EAA supplements - the supplement that is based on whey protein plus potassium citrate, L-isoleucine, ornithine alpha-ketoglutarate, L-tryptophan, taurine and L-citruline alone could have made all the difference;
3. the baseline characteristics of the randomly formed groups differed - with the VLCD group being sign. fatter (80% were obese vs. only 16.67% in the VLCKD), which is obviously a problem you cannot ignore when interpreting the results;

Against that background, you must not get all to psyched about what you see in Figure 1 - at least with respect  to the significance of the results with respect to confirming the superiority of ketogenic very low calorie diets over regular very low calorie diets... not the least, because we don't really know what the mechanism behind the benfit can be - is it: (a) reduced adrenergic influences, (b) increased production of ketone bodies that directly effect extra-hepatic tissues including brain and muscle, (c) amelioration of the blood sugar induced reduction in GH prodution or (d) high(er) / greater quality protein intakes - all that could interac with insulin and individual (epi-)genetic dispositions of the subjects.

"Keto Diet Research: Body Weight & Fat Gain, but not Muscle Protein Synthesis After Exercise is Impaired in Rodents in Ketosis" | read it

So what does the study confirm, then? It's not nothing, don't worry. After all, the study confirms that going low carb when you starve yourself and helping your muscles survive with an slightly 'enhanced' whey protein product.

Since it is not clear to which extent the previously discussed extra-advantages of the ketogenic diet group affected the study outcome, however, more and better controlled studies that are specifically designed to assess the combined effects of genotypes and dietary intervention, as well, will be necessary to make definitive statements about whether the "keto-advantage" is in fact as significant as the data in Figure 1 appears to suggest | Comment!

References:

• Fulks, Richard M., Jeanne B. Li, and Alfred L. Goldberg. "Effects of insulin, glucose, and amino acids on protein turnover in rat diaphragm." Journal of Biological Chemistry 250.1 (1975): 290-298.
• Merra, G., et al. "Very-low-calorie ketogenic diet with aminoacid supplement versus very low restricted-calorie diet for preserving muscle mass during weight loss: a pilot double-blind study." European Review for Medical and Pharmacological Sciences 20 (2016): 2613-2621.
• Woolfson, Anthony MJ, Richard V. Heatley, and Simon P. Allison. "Insulin to inhibit protein catabolism after injury." New England Journal of Medicine 300.1 (1979): 14-17.