Female Athletes' Body Composition Suffers From Chronic Energy Deficits: Effects of Energy, Protein, CHO Intake, Timing & Distribution in Gymnasts & Volleyball Players
|Even female volleyball players are wo- men - no wonder they tend to undereat ;)|
I guess many of you will remember that I've written about gymnasts before - in July 2013, to be precise. In said article with the telling title "Do Chronic Energy Deficits Make Athletes Fat? The Longer & More Severe You Starve, the Fatter You Are. Irrespective of What the Calories-in-VS-Calories-Out Formula May Say" (read more) I analyzed the negative effects of "starvation" on body composition to highlight that simply not eating or eating like a bird is not going to give you the Shape cover model body, many girls are looking for.
In spite of the fact that the titles of the two studies and hand and the previously cited study by Deutz differ, the objectives are not very different:
- "The purpose of this study was to simultaneously assess energy balance and
protein intake to determine if these factors are associated with body composition in a
population of collegiate sand volleyball players." (Richardson. 2014)
- "The objective of this study was to determine the relationship between hourly EB and protein intake with body composition" (Paszkiewicz. 2014)
Apropos subjects! In the gymnasts who participated in Paszkiewicz' study were elite and highly
competitive athletes from several training gyms across the country. The information on their daily food intakes was elucidated by the means of secondary analyses that were performed on previously collected three-day food diaries and the interactions with body composition were calculated by comparing intakes and anthropometric measures (made with DEXA).
|Table 1: Subject Characteristics of the Gymnasts (N= 40; Paszkiewicz. 2014)|
There is one general problem with the "energy balances" in both studies! Being based on the standard equations, they are - at beast - a proximate of what the women really need. For the gymnast study, the difference between energy in and out is yet large enough to safely assume, they were really starving itself. For the volleyball study, I wouldn't be so sure - specifically in view of the fact that the body has its means of sparing energy, when it's chronically getting less than it would need - the corresponding changes in thyroid & other hormones have yet not been studied by either Paszkiewicz or Richardson.If we take a closer look at the correlations Paszkiewicz found, some of you may be surprised to see that the relative carbohydrate intake (as percent of macronutrients) was not just positively associated with higher lean mass (see Figure 1), but also negatively with fat mass (R = -0.043).
|Figure 1: Minimal, maximal and average energy balance in the gymnasts (left); positive correlates and correlation coefficients R of lean mass in 40 elite competitive female gymnasts (Paszkiewicz. 2014)|
Are high(er) protein intakes bad for gymnasts or, what?
Personally I suspect that this is due to a correlation between high(er) protein intakes, lower cabohydrate intakes (R = -0.595) and, most importantly, a reduced overall energy intake, which is associated with lower lean body mass and (listen up, ladies!), just as it has been reported by Deutz et al. previously, increased body fat % (reread the corresponding article from July 2013).
But why don't we have a look at the other study? Beach volleyball players are regarded as the epitome of health and sexappeal, so things could easily look different for them compared to the "frail" gymnasts, right? With a mean body fat % of 18% and a standard deviation ±7% the twelve women from the GSU sand volleyball team who participated in Richardson's study have a much healthier body fat percentage than the average, let alone extreme gymnast in the previously discussed study (we got to be careful here, because the BF% in the Richardson study was measured by body impedance and could thus easily be 5% off).
Reduced bone mineral density is a surprising negative side effect to highe(er) protein intakes in the study at hand. According to Paszkiewicz "[h]igher protein consumption was significantly associated with lower bone mineral density(BMD)in the gymnasts at the arms (r= -0.535; p < 0.001), legs (r= 0.0523; p = 0.001), trunk(r= -0.517; p = 0.001), spine (r= -0.472; p = 0.002), and pelvis (r= -0.539; p < 0.001)." (Paszkiewicz. 2014) Previous studies have yet shown that a high protein intake, in the absence of a continuous energy deficit as it was observed in the study at hand, will not lead to brittle bones. And in an energy sufficient scenario it's rather the lack of little veggies and fruits, as well as other alkalizing foods, than the amount of protein that's to blame for previously observed correlations (Heaney. 2008).With a mean BMI of 22 kg/m², all female participants of the study were normalweight and consumed a diet with >1.94g protein per body weight (mean intake 132 ±52 g per day). An amount of protein most of the ladies spread across the day with a mean 26.06 (±10.51) g being consumed on every eating opportunity. That's not yet the "SuppVersity suggested" amount of 30g of protein per meal, but it's getting close, yet with an uneven distribution from AM to PM:
- 30g from 6-12 AM,
- 63g from noon to six PM,
- another 39g in the evening
"[...] protein intake distribution was skewed, on average, toward the latter half of the day with approximately 19% of protein consumed in the morning and 34% consumed in the evening." (Richardson. 2014)Much to my surprise, the ladies in the beach volley ball team were similarly anorexic as their peers in the gymnast group. With -404 (±385) kcal/day the average energy balance was clearly negative; and even if the standard deviations indicate that this was not the case for all of the ladies, the athletes spent 17 hours, on average, in a catabolic energy balance state (< 0 kcal) on a daily basis.
A high relative protein intake was not associated with better body composition!
Interestingly, though, no significant correlation was found between energy balance per gram of protein consumption and body composition.