Wednesday, January 7, 2015

Pseudo-Low Carb Diet With Low Fat (55g/d) Content Sheds 0.5kg/Week W/Out Muscle or Performance Loss in Athletes

If you stick to the information in the abstract it sounds like a "low carb" diet intervention. Don't be fooled!
I am not a low carb enthusiast, but I don't close my eyes to the proven benefits the modulation of one's carbohydrate intake. Benefits as they are described by Hovinen et al. (2015) in their latest paper in the Journal of Strength and Conditioning Research. In the corresponding study, the researchers from the University of Jyvaskyla and the University School of Physical Education in Wrocław in Finland and Poland, respectively, investigate the effects of a high energy deficit diet (~750 kcal/day) and a moderate one (~300 kcal/day) in athletes just before their actual competitive season.

The statement that they were evaluating the "functionality of an optimal gradual weight reduction (GWR) diet with high protein and low carbohydrate (CHO) to optimize jumping and sprint running performance while maintaining fat-free mass (FFM)," (Hovinen. 2015) is however, as the following elaborations, graphs and stats are about to show, grossly misleading, because what they really did was to evaluate the effects of a high carbohydrate, high protein, low fat diet... but we will get to that in a minute.
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For their experiment, which lasted only 4 weeks, the scientist recruited 20- to 35-year-old national and international level Finnish track and field male athletes from jumping and short distance running events (e.g., 100–200 m). The participants had at least 5-year background in competitive athletics. All participants were advised to keep their training program consistent during WRP, which was also controlled and monitored for volume and intensity each week by the researchers and the athletes’ coaches

The athletes were randomly divided into 2 groups: high weight reduction (HWR; energy deficit 750 kcal/d; n = 8) and low weight reduction (LWR; energy deficit 300 kcal/day; n = 7).
"Nutritional intake before and during WRP is presented in Table 1. Significant differences between groups in nutritional intake during WRP were observed in fat (p <= 0.05), total energy intake (p <= 0.05), and CHO (p <= 0.05), which were lower in HWR than in LWR without differences in protein intake (~2.1 g·kg-1·d-1 in each situation) as planned.
Table 1: Nutritional intake before and during weight reduction period. †Significant difference vs. before, p < 0.01; ‡Significant difference vs. LWR, p < 0.05 (Huovinen. 2015).
A significant time effect for energy intake and CHO per body mass (2 × 2 ANOVA) was observed (p <= 0.01), and although the total energy and CHO intake decreased in both groups during WRP, these changes were significant only in HWR (p <= 0.01)."
If you scrutinize the changes in the individual groups you will see that the relative reductions in protein, carbohydrate and fat intake were 0%, 15% and 14% for the LWR and 22% and 35% for the HWR group.
Figure 1: Changes in body composition over the 4-week study period (Huovinen. 2015).
Since the LWR diet had not effect on the body composition and body weight of the subjects (see Figure 1), we can focus on the HWR group, which did not - as the abstract to the study would suggest solely reduce their carbohydrate intake.
This is not a classic low carb, let alone a ketogenic diet! Rather than just cutting back carbs, the track and field athletes in the study at hand reduced their already low fat intake from 72.27 g/day to 54.67 g/day which is lower than any of the low-carb advocated would ever go. Furthermore 46% of the total energy during the dieting phase come from carbs (23% from protein, the rest from fat). We are thus talking about an energy reduced high carbohydrate high protein diet, here where a higher fat intake was associated with lower fat loss (see figure in the bottom line).
If we do the math for the relative contribution of the three large macronutrient groups, i.e. protein, fats and carbohydrates, you can easily see that the diet which produced allegedly impressive weight loss results is the diametrical opposite of a ketogenic diet.
Figure 2: Macronutrient composition of the baseline and energy reduced diets (Huovinen. 2015).
It is, as the data in Figure 2 tell you, both high in protein and high in carbohydrates. At the same time it is so low in fat that I personally am surprised that the researchers did not observe changes in any of the hormonal parameters they measured:
"There were no differences between the groups in serum hormone concentrations before and after WRP except cortisol, which was greater (p <= 0.05) in HWR than in LWR before WRP. Hormone concentrations did not differ significantly after the 4-week WRP" (Huovinen. 2015).
So, cutting your fat intake to from low to marginal, obviously cannot be that bad for highly active individuals as some of the low carb enthusiasts claim. Take a parting look at the performance data in Figure 3 (values are calculated based on the body weight at the beginning and end of the study, respectively):
Figure 3: Pre vs. post (%) changes in relevant performance markers, i.e. counter movement jump (cm) and 20m sprint times - please note that a reduction in sprint times which is by the way significant for the HWR group is a highly desirable performance increase not an unwanted performance decrease (Huovinen. 2015).
Which athlete would be pissed if dieting increases parameters that are as essential for his athletic performance as sprint performance and counter movement jumps are for a track and field athletes? Right. No athlete would. If anything the increase in pH and the marginal loss of bone mass may be of concern (see figure in bottom line for correlation).

The latter, i.e. the reduction in pH and the correlating loss of bone mass, would yet probably not be compensated by an increase in fat intake. A more effective approach that has been shown to protect the bone mass in women on high protein diet is the ingestion of potassium or sodium bicarbonate (Lutz. 1984; Sebastian. 1994).
Fat intake vs. jump performance (top) & fat free mass changes (middle) and pH change vs. bone loss (bottom).
Beware of improper interpretations of this study! Without even having read another write-up or news update mentioning this study, I can already tell you that it is going to be misinterpreted as evidence for the superiority of "low carbohydrate dieting" for athletes. Yes, the carbohydrate intake was reduced, but carbs still made up the lions share of the energy intake.

As a SuppVersity reader you are yet (hopefully) too smart to fall for bullshit claims like this. A brief glimpse at the macronutrient ratios in Figure 2 is after all enough to prove that anyone who claims the impressive fat loss results in the study at hand had been achieved by a low carb diet either hasn't read the whole publication or is simply ignored the actual macronutrient composition. Speaking of which, the latter is certainly lower in fat than what I have recommended previously on the SuppVersity. If you look at the correlation between fat intake (%) and changes in fat free mass in the graph to the right, a bit more fat probably wouldn't have hurt any of the athletes, even though it correlates with reduced counter movement jump performance. What is in line with the 9 rules of sensible dieting is the energy deficit which ~24% below maintenance | Comment on Facebook!
  • Huovinen, H. et al. "Body Composition and Power Performance Improved After Weight Reduction in Male Athletes Without Hampering Hormonal Balance." Journal of Strength & Conditioning Research: January 2015 - Volume 29 - Issue 1 - p 29–36.
  • Lutz, Josephine. "Calcium balance and acid-base status of women as affected by increased protein intake and by sodium bicarbonate ingestion." The American journal of clinical nutrition 39.2 (1984): 281-288.
  • Sebastian, Anthony, et al. "Improved mineral balance and skeletal metabolism in postmenopausal women treated with potassium bicarbonate." New England Journal of Medicine 330.25 (1994): 1776-1781.