It's been about a year since I moved from vegetarianism to including animal protein in my daily nutrition plan and happily living the controlled carbohydrate, higher fat lifestyle. I wanted to do a short blog to describe where my metabolic efficiency is at today and explain a few things in the process. Here is my metabolic efficiency (ME) assessment as of yesterday.
The assessment was done on the treadmill, beginning at 8:27 minute/mile and progressing to the last stage of 6:19 min/mile. As you can see, I did have an MEP but my fat burning abilities were much less pronounced versus one year ago (look at the %'s to the left of my MEP). I will explain why that is soon. What I did differently this time around was measure my blood lactate to attempt to correlate LT (lactate threshold) with MEP (metabolic efficiency point). My MEP happened about :30 before my LT which indicates that my nutrition could better support my current fitness level. Keep in mind that I normally do not do ME and LT testing in the same test because they are looking at different variables. ME testing is not meant to test for threshold or even go that high in intensity while LT testing is only looking for the point in time where lactate clearance cannot keep up with lactate production (we do this to set heart rate and pace/power zones for athletes). Additionally, the pre-test protocol for ME testing is a 12 hour fast while pre-LT test protocol calls for entering the test just like you would a race, following the same nutrition plan with only about a 2 hour fast before.
I have been controlling my daily carbohydrate intake throughout this past year but it cycles daily and weekly based on my training needs (I call this microcycle nutrition periodization). I have been experimenting with adjusting my carbohydrate intake between 60-120 grams per day, mostly dependent upon my energy needs to support higher intensity triathlon and cyclocross training. That said, in the weeks leading up to my most recent ME assessment, I averaged roughly 100 grams of carbohydrate per day.
I was happy to see where my MEP was but take a look at where it was the month after I started eating meat again (October, 2012) and limiting my carbohydrate intake to 60-80 grams per day.
The intensity change per stage was the same with the exception that my last stage was a 6:31 min/mile. Yesterday, I was able to go one more stage (to a 6:19 min/mile), mostly because I have been training with higher intensity for cyclocross racing and am building into a reverse periodization triathlon training plan for 2014. What is very interesting is the overall amount of fat vs. carbohydrate that I was burning in my ME assessment last year versus this year. Today, while I am burning a decent amount of fat before my MEP, it is much less than one year ago.
Why you may ask? Pretty simple actually. Combine my eating 20-40 more grams of carbohydrate per day along with pretty high intensity exercise and you get less fat burning. Nothing that would raise a red flag but nonetheless, still a lower amount. The take-home message for me is that lowering my daily carbohydrate intake to around 60-80 grams yields a higher state of metabolic efficiency. This is for my body as everyone will be different based on their training, genetics, carbohydrate intolerance and daily nutrition plan.
As I continue to cycle my daily carbohydrate and fat intakes in search of the right equation that yields the "biggest bang for my buck", I will continue my ME testing more often during this off-season. While there really isn't a technical definition of "low carb", I do believe that an ideal range exists for each athlete. One that yields both optimal metabolic efficiency and performance while having the ideal body weight and body composition. It's a fun exploration and I will continue to report my progress. Hopefully, there are some take-aways for you also in relation to changing your daily nutrition plan to improve your body's ability to burn more fat.