|Image 1: Even if the boys in the study at hand still ate "more calories than they expended", HIT would certainly slow their progress from the healthy kid in the left to the obese and more importantly unhealthy one on the right.|
HIIT holds the key to health and satiety... and that is probably why it facilitates weight loss!
When I think about it, for a morbidly obese person, taking the stairs could in fact be even more intense than the 75% VO2Max high-intensity cycling protocol the 15 obese boys (age 13.5y; BMI: 30.7; waist: 104.3cm; fat mass 38.2%) from the Pediatric Obesity Department of the Children’s Medical Center of Romagnat (France) performed at roughly 3h after ingesting a standardized breakfast, the caloric content of which was matched to the calculated energy expenditure, i.e. rest + exercise-induced (the boys had to cycle until they had performed a workload equivalent to ~350kcal) of the entire morning in order to isolate the effect of exercise intensity from that of energy status on subsequent energy intakes at launch and dinner, as well as macronutrient pereferences, energy expenditure and appetite sensation, which were the other dependent variables, David Thiel and his colleagues recorded after the aforementioned high intensitiy and separate (7-days washout) low intensity (40% VOMax, again 350kcal) exercise and sedentary control conditions.
|Figure 1: Energy intake, expenditure and balance of the boys in the three test sessions (calculated based on|
A brief note on the notion of "dietary interventions": For15 year old boys who habitually consume >3500kcal/day any "dietary intervention" to prevent them from morbid obesity, diabetes and all the other ailments by which large parts of the Western society is plagued, must inevitably include a reduced calorie intake! While the importance of the daily "energy balance" is certainly overblown and any holistic diet + exercise + lifestyle intervention should be designed to induce a natural, satiety-induced reduction in energy intake by combining a reasonable amount of intense exercise with a nutrient-dense diet like, but not necessarily identical to a low-, but - in most cases - better not no-carb "Paleo Diet", complete ignorance towards the amount of food you consume will inevitably compromise your results - no matter how "good" the calories you are consuming may be.In this context, it is also noteworthy that the reduction in calorie intake in the HIT trial was more pronounced at dinner than at launch and that the non existent differences between the ratings of subjective hunger, fullness or prospective food consumption in the three experimental sessions, cannot be accounted for by changes in the macronutrient composition of the subsequent ad-libitum meals, which were equally "identical" (within statistical margins, obviously) for the high intensity, low intensity and sedentary control session.
Hard and short = full and happy - what more can you ask for?
|Image 2: I guess if parents were better role-models and encouraged their children to exercise (with them), childhood obesity would not be such a huge problem, anyways.|
While the very different exercise stimuli of HIT (Thiel study) and HIIT, on the one hand, and resistance training (Belaguera-Cortes study), on the other hand, could account for the differential effects on subsequent energy intake and would thusly support the notion that resistance training alone is not sufficient to induce significant reductions in body weight.
I feel that further research is needed to establish, the influence of being obese or lean and/or being used to overeat vs. eating at maintenance exerts on the resistance exercise-induced increase in energy intake and the long-term effects of the latter not on body weight, but body composition.