The Best Fat Loss Program?
Diet and hormones aside, it’s hard to argue that your ability to lose fat is ultimately determined by your body’s state of energy balance – and your exercise program must therefore be tailored to elicit the greatest amount of energy expenditure possible. The million dollar question is, What’s the best way to do this?
You may recall from previous posts (HERE, for example) discussions about EPOC (excess post-exercise oxygen consumption, i.e. recovery oxygen consumption or “afterburn”). In layman’s terms, this is the oxygen (and, in turn, fat) we burn when we recover after exercise. It has both fast (minutes) and slow (hours, and sometimes even days) components, during which the body utilizes oxygen at a rapid rate to replenish energy stores (ATP and creatine phosphate), as well as remove exercise byproducts (lactate) from the blood. (Note: The slow component and lactate’s effects on energy need A LOT more research, as lactate can be metabolized in various ways. BUT, we no longer believe the slow component of EPOC is related to lactate.)
EPOC is all the talk in the fitness world these days; unfortunately, we haven’t really figured out exactly how best to produce or measure it (although we do know it exists, and I personally believe it can contribute significantly to total energy expenditure with the right protocol). In fact, we don’t really know how to measure total energy expenditure at all – especially when it comes to anaerobic exercise.
From our work in the lab, EPOC seems to be linearly related to exercise duration and EXPONENTIALLY to intensity – which means it’s probably greatest when we work hard for a relatively long time. But the harder we work, the more we rely on our anaerobic systems to provide fuel – yet we measure energy expenditure and EPOC by predominantly aerobic means (i.e., oxygen uptake and an energy conversion calculation based on aerobic metabolism). So, our measurements probably don’t accurately reflect anaerobic contributions to energy expenditure or the EPOC of non-steady-state (anaerobic) forms of exercise like resistance training, high-intensity intervals, and stop-and-go competitions like the French Open and Spartan Sprint!
Not just a random choice of anaerobic activity there; a bunch of my coworkers and I actually competed in it this past Saturday. In addition to running uphill (and trying not to fall on the way back down), we had a blast climbing over walls, carrying buckets of rocks up a mountain, jumping over fire pits and crawling under barbed wire through the mud…
I have no idea how much energy we burned or EPOC we elicited, but all we definitely worked hard and did pretty well, if I do say so myself!
But back to the topic at hand: We’re getting there with the measurements…Without belaboring the science too much more, because the substrates that fuel the anaerobic and aerobic systems are different (glucose, lactate and creatine phosphate versus fat), we now use a different formula to convert recovery oxygen consumption (EPOC) to energy expenditure when exercise is anaerobic. More importantly, because circuit strength training and intervals seem to produce greater fat loss in practice and experimental research, we’re looking a bit closer at the anaerobic contribution to exercise energy expenditure. To no surprise, we’re finding that it’s probably greater than we used to think (regardless of EPOC).
For example, a recent study published in the Journal of Strength and Conditioning Research found that the anaerobic and EPOC contributions to energy expenditure were both greater than the aerobic contribution (exercise O2 consumption) during both strength- (as in 5-15 repetitions) and endurance-based (20-40 reps) sets of the bench press to muscle failure. Keeping in mind that the methods used to measure anaerobic energy expenditure and EPOC are questionable (the use of blood lactate is highly controversial and the anaerobic EPOC formula, even if valid, still only accounts for the slow component), the study does give reason to think we’ve been underestimating the energy expenditure of resistance training by only looking at oxygen consumption.
Interestingly, the study also found that endurance-based sets resulted in virtually the same amount of EPOC as strength-based protocols… BUT, total energy expenditure (exercise aerobic, exercise anaerobic and recovery/EPOC) and total work (load x distance) were both greater for endurance versus strength. EPOC didn’t seem to be related to aerobic or anaerobic energy expenditure, or to total work performed – so it’s still a bit of a mystery…
But without considering the elusive EPOC, it seems total energy expenditure is greatest when the greatest amount of total work is performed – and we can definitely use this bit of information when creating exercise programs for fat loss: The best way to lose fat through anaerobic exercise is probably to just get as much work done as possible. Given that intensity and duration are inversely proportional, what this means for a resistance training program is that lifting should be done at a relatively high but submaximal intensity that allows you to work for a sufficient amount time (what constitutes “sufficient” has yet to be determined). But given real-world time constraints, you’d be wise to carefully group your exercises so that minimal time is spent resting (i.e., NOT doing work). HINT: Circuits, supersets, escalating density training, etc. – and these types of training also produce favorable hormonal responses.
When it comes to interval training, the same rule of thumb likely applies. Again, we’re not exactly sure of the best work: rest ratio or protocol to follow, but given the above study’s findings, it stands to reason that we’d want to perform the greatest amount of work possible to expend the greatest amount of total energy (again, working at high but submaximal intensities that allow you to work for a pretty long duration).
Another study in the JSCR shines some light on this matter. Although the study was concerned with performance measures rather than energy expenditure, when researchers compared four cycling interval training protocols of varying intensities and durations, they found that subjects were able to spend the most total time at high intensities and consume the most total oxygen when they worked at 90% of their maximum power output and followed a 30 seconds on: 30 seconds off protocol – likely because their blood lactate concentrations remained lower than when they exercised at 100% of maximum power output or used intervals of longer duration (three minutes). If only I had remembered that during the Spartan race…
As previously mentioned, EPOC seems to be linearly related to exercise duration and exponentially to intensity, so reason would suggest that a 30:30 protocol not only results in greater exercise oxygen consumption, but also in greater recovery oxygen consumption (EPOC). In any case, it does seem that total exercise energy expenditure is related to total work performed – and the 30:30 protocol ultimately resulted in more total exercise time.
BOTTOM LINE: There’s still a lot we don’t know about EPOC and the total energy expenditure of exercise, including how best to measure them and use them to our advantage. At this point, we’d be wise to also look at empirical evidence: What’s worked for us in the past? What are guys like Alwyn Cosgrove doing that produce results?
That said, the above studies do suggest that current practices employing high-rep resistance training programs and 30:30 interval protocols that result in a large amount of total work performed would certainly be favorable ways to lose fat. Is there a better way? Only time will tell…
For now, it looks like Coach Dos has it right:
Filed under: exercise programs, exercise research, fat loss
