Dukan Diet

More Than 2kg Body Fat in 4 Days Manic Exercise and a 4 Day x 5 000kcal Energy Deficit on Whey or Sucrose Based Starvation Diet Yield Astonishingly Long Lasting Fat Loss

Actually, even cherry tomatoes were not allowed in the first 4 days ;-)

Wow! If thats what you thought, when you read the figure in the headline you know what I thought, when I spotted the latest paper from the University of Las Palmas de Gran Canaria in the "ahead of print" section of the Scandinavian Journal of Medicine & Science in Sports (Calbet. 2014).

I mean, the title of the study, "a time-efficient reduction of fat mass in 4 days with exercise and caloric restriction", sounds pretty harmless. Too harmless for what happened to the 15 subjects the researchers recruited for an experiment that was almost as extreme as its astonishing results.

Wake up, work out, starve and sleep

I would say the above summarizes pretty well what I was referring to, when I said "something happened to the subjects" in the first 4 days of the study, the 15 not exactly lean study participants (mean BMI ~30kg/m²; body fat 31%) started their days with 45min of an arm cranking exercise (at 15% maximal intensity; see Figure 1).

Figure 1: Schematic overview of the different phases of the diet + exercise intervention (Calbet. 2014)

When they were done, they spend most of the remaining waking hours day walking - 8 h of walking at 4.5 km/h (35 km/day) 4 days in a row and on a diet delivering meager 3.2 kcal/kg body weight from a shake that contained either pure whey protein or pure sucrose.

This cant really be the whey to go? Right?

What sounds like some mad survival program did, as you can see in Figure 1, produce quite impressive weight loss effects. Unfortunately, this is "weight", as in fat and muscle and that at an almost 1:1 ratio - certainly not the type of "weight loss" any of you should strive for.

Figure 2: Lean mass (left) and fat mass (right) development during the four phases of the intervention (Calbet. 2014)

Now, the fat rebound in the sucrose group would initially suggest that your gut feeling was right. Eventually, its yet unlikely that this was more than a mere coincidence and the shocking loss in lean mass that occurred during the 4-day of manic dieting + walking, normalized withing days, when when the subjects returned to their regular energy intakes (+ obligatory 10,000 steps a day).

The latter obviously suggests that most of the "muscle loss" was actually water + glycogen and thus easy to restore (see Figure 3, right, as well).
What I cannot explain - at least not without telling you that my answer is of hypothetical nature and would thus require experimental confirmation - are the impressive long(er)-term weight loss effects.
Usually you would expect the subjects to jojo back up, right away - in the worst case to body fat levels that are higher than those nasty 31%, where they were initially coming from. If you take a look at Figure 3, its yet plain to see that the opposite was the case.

Figure 3: Progressive changes in body fat and lean mass (in kg) over the course of the study period (Calbet. 2014)

In spite of the fact that the subjects returned to their regular energy intakes, they lost an additional body fat - at quite an impressive rate, by the way. Now, an as previously mentioned hypothetical explanation for these observations is the use of body fat as a substrate and energy source to refill the previously mentioned glycogen stores in muscle and liver.

Even if we take into consideration that the release (lipolysis) and oxidation of fats and the storage of glucose from dietary carbohydrates (its not impossible (Kaleta. 2012), but unlikely that the stored body fat is used as an energy source for glyconeogenesis) in form of glycogen are energetically costly, the 2,000kcal would equal no more than max. 300g of stored body fat, which is more than the additional 450g even the whey protein group dropped during the 4-day aftermath.
References:

• Anderson, James W., et al. "Long-term weight-loss maintenance: a meta-analysis of US studies." The American journal of clinical nutrition 74.5 (2001): 579-584.
• Calbet, J. A. L., et al. "A time-efficient reduction of fat mass in 4 days with exercise and caloric restriction." Scandinavian Journal of Medicine & Science in Sports. (2014). Accepted Manuscript. doi: 10.1111/sms.12194 
• Garrow, J. S., and C. D. Summerbell. "Meta-analysis: effect of exercise, with or without dieting, on the body composition of overweight subjects." European journal of clinical nutrition 49.1 (1995): 1-10.
• Kaleta, Christoph, Luís F. de Figueiredo, and Stefan Schuster. "Against the stream: relevance of gluconeogenesis from fatty acids for natives of the arctic regions." International journal of circumpolar health 71 (2012).
• Kreitzman, Stephen N., Ann Y. Coxon, and Kalman F. Szaz. "Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition." The American journal of clinical nutrition 56.1 (1992): 292S-293S.
• Persky, Adam M., and Gayle A. Brazeau. "Clinical pharmacology of the dietary supplement creatine monohydrate." Pharmacological Reviews 53.2 (2001): 161-176.
• Ribeiro, Alex S., et al. "Resistance training promotes increase in intracellular hydration in men and women." European journal of sport science ahead-of-print (2014): 1-8. 
• Shaw, K., et al. "Exercise for overweight or obesity." Cochrane Database Syst Rev 4 (2006).
• Vilsbøll, Tina, et al. "Effects of glucagon-like peptide-1 receptor agonists on weight loss: systematic review and meta-analyses of randomised controlled trials." BMJ: British Medical Journal 344 (2012).
• Willis, Leslie H., et al. "Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults." Journal of Applied Physiology 113.12 (2012): 1831-1837.