AM Cardio for Fat Loss W/ 25g Casein vs. 25g Whey Isolate, 25 g Maltodextrin Preload, or Truly Fasted – What’s “Best”?
|Don’t believe a word when someone tells you that a new study would show that you can burn extra body fat if you consume a casein shake before your (by then no longer fasted) AM cardio workouts.|
While the scientific evidence doesn’t seem to confirm the superiority of fasted AM cardio (learn more), there’s no doubt that it can help you shed body fat if the energy you expend on treadmill ergometer, or rowing machine helps you sustain a >10% energy deficit over the next 24h.
A final answer to this question has yet to be found, but with the results of a recent study by Bradley T. Gieske and colleagues from the Lindenwood University (Gieske 2018), this ostensibly super-important question *rofl* may become redundant, anyway…
- 25g protein in form of 25 g of similarly colored and flavored whey protein isolate, of casein protein (real micellar casein, no cheap caseinates), and compared the effects of this protein preload to 25 g of maltodextrin, or a non-caloric control.
After the ingestion of the supplement, the participants sat quietly for 30 min before completing a standardized warm-up protocol consisting of whole-body dynamic movements that lasted approximately ten minutes. Hence, the actual testing session, a medium-to-low intensity 30-minute ‘cardio’ session on the treadmill (55% heart rate reserve) took place 40 minutes after the bolus ingestion of casein, whey, maltodextrin or the zero-calorie control drink.
|Figure 1: Acute exercise-induced (kcal total on the primary axis) and extrapolated post-exercise 24h energy expenditure (kcal/kg/day on the secondary axis) in the study by Gieske et al (2018).|
the researchers’ hypothesis “that pre-exercise protein ingestion would increase post-exercise energy expenditure and fat oxidation compared to both carbohydrate and fasting conditions” (
- Dietary standardization in form of a replication of the average four-day diet composition reported by participants prior to Visit 1 was as follows: 2446 ± 800 kcal (28.44 ± 9.30 kcal/kg), 132 ± 56 g (1.53 ± 0.65 g/kg) protein, 235 ± 101 g (2.73 ± 1.17 g/kg) carbohydrate, 99 ± 37 g (1.15 ± 0.43 g/kg) fat on the remaining test visits was successful.
- Exercise standardization as measured using one-way ANOVA revealed no significant differences (p = 0.743) in intra-exercise heart rate, rating of perceived exertion (p = 0.985), or oxygen consumption (p = 0.993) between conditions, suggesting that intensity was sufficiently standardized across all testing sessions.
- And the pre-treatment and pre-exercise rates of energy expenditure (Absolute: 1873 ± 189 kcal/day, Relative: 22 ± 2 kcal/kg/day) were not significantly different across conditions (p > 0.99).
#Evidence: Meta-analysis says: “Fasted AM Cardio – No Measurable Physiological Benefits in Terms of Fat Loss & Body Composition” | more
the energy expenditure after consuming the whey protein isolate (WPI | 3.41 ± 1.63 kcal/kg) was significantly greater (p < 0.05) than the within-group change in REE following consumption of maltodextrin (MAL | 1.57 ± 0.99 kcal/kg, p = 0.010) and tended to be greater than the non-feeding control group (2.00 ± 1.91 kcal/kg, p = 0.055);
- similarly, the energy expenditure after consuming the casein protein (CAS | 3.38 ± 0.82 kcal/kg) was greater than those following consumption of MAL (p = 0.012) and tended to be greater than the non-feeding control group (p = 0.061)
So far, so good, now for the bad news: With a total intra-exercise EE of 345 ± 31 kcal, 362 ± 32 kcal, and 349.17 ± 70 kcal, the increase in energy expenditure compared to the control trial (293 ± 37 kcal) is below the amount of energy, circa 100kcal, in the protein/carbohydrate supplements.
|Figure 2: Individual effects on energy intake and expenditure (left) and corresponding net effect (right).|
You can see that very well if you check out the subjects’ energy balance right after the workout (Figure 2, left); and things don’t look much better if we assume that the post-workout increase in energy expenditure persists, i.e. that the scientists’ calculated “increase in energy expenditure” remains stable (or whatever they assumed it did, when they used the data from 20-25 minutes after the workout and extrapolated it to 24h), and calculate the effect of consuming whey, casein, or maltodextrin on the net energy balance.
Do not get me wrong, though… AM cardio aids fat loss!
|#Popular: “Ever Wondered Why the Fat Keeps Falling Off When You Embark on Intermittent Fasting Regimens? Calories, Bro!” | read more|
I’ve experienced that repeatedly, myself. For me, personally, doing AM cardio means doing cardio at all. If I postpone it to “later”, it is not unlikely that I don’t do it at all and fail to burn those extra 300-500kcal which are then not missing from my net energy balance – a balance I deliberately keep in the red while dieting, ’cause there’s no metabolic magic in AM cardio that would make the fat fall off, it is pretty much like “fasting”: It’s all about calories … well, calories, coffee (’cause you always need it 😉 and weight training + enough protein to optimize your lean mass retention aka “keep your gainz” 😉
- Gieske, et al. (2018). “Metabolic impact of protein feeding prior to moderate-intensity treadmill exercise in a fasted state: a pilot study.” Journal of the International Society of Sports Nutrition 15:56.