I’m going to share a couple case studies I came across to illustrate an important point, that having a large energy deficit and a very high activity level is a recipe for failure. There’s also plenty of evidence here that cardio itself doesn’t help fat loss either…
The first example is common. This study was also discussed in great detail by Lyle McDonald. A woman began marathon training sessions with a reported low-calorie diet, and instead of losing weight, either maintained it or gained more. Her metabolic rate was also below normal.
Once diet was corrected and energy intake was increased gradually, her BMI came down and her metabolic rate increased.
That said, I’ve mentioned in previous articles that one oddity that I’ve seen (and personally experienced) over the years is one where the combination of very large caloric deficits and very large amounts of activity (especially higher-intensity activity) can cause problems for people either stalling or slowing fat loss.
The second example regards a young man trying to drop fat rapidly in order to pass a Navy diving exam and increase endurance capacity. You can read the full discussion by Jamie Scott here. He had a very high training regimen that included Crossfit, fasted training, lots of glycolitic work.
Once he dropped the activity level down substantially, and began comsuming more food, fat loss and energy levels improved rapidly.
Just a quick message to say the article is great. The fat is falling off me like it never actually has before and I’m feeling fuelled for every workout. I honestly can’t thank you enough. Coconut milk and cream have become my new best friends and I am talking everyone’s ears off at the gym with how good they are. I will keep in touch with the progress as I think something a bit crazy (good crazy) might be happening here, exciting.
So what’s going on here? We have a young man and an older woman, both trying to lose fat rapidly, following the conventional wisdom of eating less and jacking activity levels up, but they are moving backwards in terms of progress!
One important factor here is cortisol. It’s a stress hormone released by the body in response to pretty much all kinds of stress. Even though we hear a lot about it in the fitness world and it gets a bad rep, it’s really a necessary component of a healthy functioning body. Acute pulses can tend to be beneficial and cause adaptive changes, but chronic elevated cortisol levels start to become problematic.
For example, the morning cortisol pulse helps to promote fat mobilization. In contrast, a chronic elevation of cortisol (especially in the face of high insulin levels) tend to promote visceral fat accumulation. As a non-fitness related topic, acute pulses of cortisol tend to be good for memory (why we often remember stressful situations in such detail) while chronic elevations (as often seen in depression) make memory go down the toilet. And there are endless other examples of where acute cortisol pulses are good and chronic elevations are bad; again see Sapolsky’s book for details.
In any case, dieting in general is a stress. And of course training is a stress. And the more extreme you do of each, the more of a stress occurs. And I suspect that a lot of what is going on when folks try to combine excessive caloric deficits with massive amounts of activity is that cortisol just goes through the roof (there’s another issue I’ll come back to at the end that relates to this). Simply, you get these massive chronic elevations in cortisol levels.
Tangentially, this is also one reason I suspect that various types of cyclical dieting help with some of this issue. For at least brief periods, when calories are raised to maintenance or above, you break the diet/training induced elevations in cortisol. This of course assumes that the person isn’t mentally stressed to the nines by raising calories like that but I’m getting ahead of myself.
Lyle, I couldn’t have put it better myself. Other things are also negatively affected by chronic cortisol production. It can cause water retention, leptin resistance in the brain, and even lower your metabolic rate. One study revealed that only 6 hours of cardio per week, combined with a “diet”, caused a larger decrease in metabolic rate than the “diet” alone! I don’t even approach that in my own training, but I’m sure most people who are addicted to cardio can easily go above and beyond that 6 hours.
In any case, there are several different plausible mechanisms by which the combination of excessive caloric deficits an large amounts of activity can cause problems. Whether it’s simply cortisol related water retention, a drop in metabolic rate due to leptin resistance or something else, something is going on. From a more practical standpoint, for a lot of people, the combination simply doesn’t work. Mind you, some seem to get away with it but not all.
Now if we go back to the young man’s case. Let’s take a look at what he was eating.
Let’s put some numbers around this. This is the approximate breakdown of this gentleman’s daily intake;
- Energy: 1732 kcal
- Protein: 162.5g
- Carbs: 129.2g
- Fat: 67.8g
And here was the workout regimen he was using.
4 x week run as per Crossfit Endurance – 1 x short intervals (10×400 usually), 1 x long intervals (6-8km of 200,400,800,1000 at 10k/5k race pace), 1 x stamina (2.4,4,5,10k TT) and 10×100 sprints/4×500 hill sprints alternated each week.
3 strength sessions – 5×5 Back squat and bench, 5×5 front squat and press, 5-5-5-3-3-1 deadlift
5 or 6 CF wods as per my box or something via sealfit/military athlete wods.
Swim twice a week, 1 x intervals and 1 long for recovery.
Ride the road bike 10k round trip to the box.
Rest Thursday AM and Sundays.
Usually do endurance workout in AM, Strength/WOD in PM. I also add in specific training for my pushup/situp/pullup as required by the navy gig.
Wow. Simply not enough energy consumed to fuel all that activity! No wonder he was feeling worn out constantly, and his fat loss was stalled completely!
Edit 4/18/12: Here is one more example from Mark’s Daily Apple. It’s a success story of a marathon runner who continued to put on steady body fat, and never was able to lose it even while training for a London marathon. He was following the conventional wisdom of eating and training which included lots of cardio. Again, a perfect example of how cardio does not help you lose fat.
I’m not going to go into much more detail here. You can check out both of those discussions I linked to on your own. But basically there are some lessons to be learned from all this.
- Fasted training and intermittent fasting has their place, but to reap the benefits you have to have plenty of food during your feeding window to meet your activity requirements. This allows a slight energy excess for training, while giving an energy deficit for fat loss during the fasted phase. Once you get down to very lean levels (roughly 10% for men and 14% for women) a slight energy deficit will work to slowly get you down to single digit bodyfat.
- If you’re in a rush to lower BMI before some deadline, you are more likely to default to some conventional wisdom crap that will have you wasting time on a treadmill in the futile pursuit of less body fat.
- The combination of major energy deficits and very high activity will set you backwards in terms of fat loss goals, and will waste a lot of time! It hurts rather than helps.
- You can either cut energy intake hard, or increase activity levels hard, but you CAN’T do both. Your body will resist.
- Some people (rarely) can get away with doing both. But they’re just lucky.
- For most of us, fat loss and fitness goals can be met with the proper types of foods, and a relatively moderate activity level. (I mean lifting HEAAAVY things once in a while, and running really really fast every now and then) Once you are eating right and doing the right activity every once in a while to make your body adapt properly, your body will take care of the rest.
This is why I so strongly suggested AGAINST the inclusion of much cardio in The Rapid Fat Loss Handbook; it causes more harm than good. Invariably, the biggest source of failure on that plan is when people ignore my advice and try to do a bunch of cardio. And fat loss stops.
In any case, there are several different plausible mechanisms by which the combination of excessive caloric deficits an large amounts of activity can cause problems. Whether it’s simply cortisol related water retention, a drop in metabolic rate due to leptin resistance or something else, something is going on. From a more practical standpoint, for a lot of people, the combination simply doesn’t work.
Thanks, Lyle, for that beautiful wrap-up.
Like this post? Want to find out more about how to get in shape fast? Check out these articles about getting in shape, feeling great, and controlling your genes!
Lose stubborn body fat. (Intermittent fasting)