A practical
carbohydrate threshold appears to exist where further reductions negatively
impact performance and put one at risk for LBM losses. Find out how much carbs you need in a diet.
Longland et al. (1)
Previously I examined this study in the context of protein intake. Now it is
time to look at the carbohydrate content and relate it with other studies, such
as Pasiakos et al (2013) I also covered before.
To recapitulate, this study experimented with different amounts of
protein and exercise during an energy
deficit of 40% for 4 weeks. Subjects were overweight but not obese and were randomly assigned (n = 20/group) to consume either a lower-protein (1.2 g/kg) control diet
(CON) or a higher-protein (2.4 g/kg)
diet (PRO). Participants were provided with all meals
and beverages to consume throughout the intervention period. The control group
consumed 15% protein, 50%
carbohydrates, and 35% fat vs. 35% protein, 50% carbohydrates, and 15% fat in the PRO group. Both groups consumed the same carbohydrate
content at 50%.
After 4 weeks LBM
increased in the PRO group (1.2 kg) and to a greater extent compared with
the CON group (0.1 kg). The PRO group
had a greater loss of fat mass than did the CON group (-4.8kg vs. -3.5 kg).
Note that even the control group with
1.2g/kg of protein was able to maintain LBM.
Mettler et al. (2)
In this study, 20 young healthy resistance-trained athletes were
examined for energy expenditure for 1 week and fed a mixed diet (15% protein,
100% energy). During week 2, all subjects were provided with food containing
100% of their habitual energy with a macronutrient composition of 50%
carbohydrate, 15% protein, and 35% fat.
In weeks 3 and 4 they followed a hypoenergetic
diet (60%) and were allocated either to the control group (50.2% carbohydrate, 15% protein (1g/kg),
34.8% fat) or to the high-protein group (50.8%
carbohydrate, 35% protein (2.31g/kg), and 15% fat).
Total (−3.0 ± 0.4 and −1.5 ± 0.3 kg for
the CP and HP, respectively) and lean body mass loss (−1.6 ± 0.3 and −0.3 ± 0.3 kg) were significantly larger in the CP compared
with those in the HP.
Garthe et al. (3)
The aim of this study was to compare changes in body
composition, strength, and power during a weekly body-weight (BW) loss of 0.7%
slow reduction (SR) vs. 1.4% fast reduction (FR). Twenty-four athletes followed
energy-restricted diets promoting the predetermined weekly WL. They consumed
about 1.2–1.8 g/kg of daily protein, 3.2–3.6
g/kg of daily carbohydrate (54-55.5%) and ≥20% of fat.
BW and fat mass decreased in both SR and FR by 5.6% ±
0.8% and 5.5% ± 0.7% (0.7% ± 0.8% vs. 1.4% ± 0.4%/wk) and 31% ± 3% and 21 ± 4%,
respectively. LBM increased in SR by 2.1% whereas it was unchanged in FR.
Pasiakos et al (4).
This study found
that lean mass retention tended to be
greater in a group consuming 1.6 g/kg/day versus a group consuming 2.4 g/kg/day
(7). In this study subjects received protein diets of 0.8g/kg (RDA), 1.6
g/kg (2x RDA) and 2.4 g/kg (3x RDA) for periods of 21 days with 40% of energy deficit.
Dietary fat accounted
for no more than 30% of total energy, and carbohydrate
provided the remainder of the prescribed energy.
After simple math, carbohydrate
percentages were 57%, 44% and 27% for RDA, 2xRDA and 3xRDA groups,
respectively.
Overall,
volunteers lost 3.2 kg during the 21-d ED; 3.5 kg for RDA, 2.7 kg for 2xRDA, and 3.3
kg for 3xRDA. The 2x
RDA group lost more fat mass (70.1%) followed by the 3x RDA (63.6%), and then
RDA (41.8%). Lean body mass loss was lower for the 2x RDA (29.9%) followed by
the 3x RDA (36.4%) compared to RDA
(58.2%). Results indicated then that the 2x
RDA with 1.6g/kg lost more body fat and the less lean body mass and was
better in both regards than 3x RDA.
Kistler et al. (5)
In this case study, the athlete undertook a
calorically restrictive diet for a 26-week preparation to a bodybuilding
contest. At the start of contest preparation, the bodybuilder consumed 250
g protein, 240 g carbohydrate, and 70 g fat per day on 5 days of the week (2590kcal 37% carbs). On 2
high-carbohydrate days evenly spaced throughout the week, 225 g protein, 400 g
carbohydrate, and 65 g fat was consumed daily.
When rate of weight loss slowed,
a 5 to 10g reduction in daily fat or carbohydrate intake was implemented to maintain
weight loss. At the end of contest preparation, the bodybuilder was consuming
250 g protein, 140 g carbohydrate, and 51 g fat per day on 5 days of the week (2019kcal 27% carbs) and 225 g protein,
255 g carbohydrate, and 46 g fat per day on two days of the week.
Since carbohydrate intake was variable I will use a value
of 32% for the table at the end. Body weight
dropped from 91.1 to 71.1 (-20kg) and percent body fat dropped from 17.5 to
7.4% (-10.4kg) during preparation. There was also a reduction in lean mass (–8.8%, 6.6kg).
Note also that bone mineral content/density increased.
Rossow et al
(6).
This case study tracked a drug-free male bodybuilder
(age 26–27 y) for the 6 months before and after a competition.
Initially during the preparation period, the subject’s
daily macronutrient breakdown was 36% protein (PRO), 36% carbohydrate (CHO),
and 28% fat for 5 days per week and 30% PRO, 48% CHO, and 22% fat for 2 days of
the week. During the preparation period, overall caloric intake did not change dramatically,
but modest (5–10 g) weekly reductions in CHO and/or fat were made based on the
progression of weight loss. Just before competition, the daily macronutrient breakdown
was 46% PRO, 29% CHO, and 25% fat.
Percent body fat declined from 14.8% to 4.5% during
preparation and returned to 14.6% during recovery. Strength decreased during
preparation and did not fully recover during 6 months of recovery. Testosterone
declined from 9.22 to 2.27 ng/mL during preparation and returned back to the baseline
level, 9.91 ng/mL, after competition. During competition preparation, fat-free mass did not decrease greatly (–3.9%,
2.81kg).
Robinson et al. (7)
This case
study documents a structured nutrition and conditioning intervention followed
by a 21 year-old amateur bodybuilding competitor to improve body composition. Absolute
(relative) carbohydrate, fat, and
protein intake over the 14 weeks was 100
± 56 g/d (20 ± 3% energy), 79 ± 17 g/d (37 ± 4% energy) and 212 ± 13 g/d
(45 ± 8% energy), respectively.
It looks from the table that there is a lower threshold for carbohydrate
intake bellow which more lean body mass is lost, in other words carbohydrate intake below a certain
threshold ceases to be protective of lean body mass. All studies and groups
(except RDA in Pasiakos et al) had higher/high protein, and the weight loss
rate per week was around the same at 0.5-1.0 % BW (1.4% BW/week in the higher
protein group for Longland et al.).
It looks like when carbohydrate intake drops below 32% it ceases to be
protective of lean body mass. I would say, keeping carbohydrate intake above
32-35%, or more precisely perhaps above 2g/kg is advisable to spare lean body
mass as much as possible.
(Robinson et al. had some issues with the training program that probably
also contributed to the greater loss of lean body mass).
Would you like to know more?
References
1. Thomas M Longland, Sara Y Oikawa, Cameron
J Mitchell, Michaela C Devries, and Stuart M Phillips. Higher compared with lower dietary protein
during an energy deficit combined with intense exercise promotes greater lean
mass gain and fat mass loss: a randomized trial. Am J Clin Nutr 2016;103:738–46.
2. Mettler S, Mitchell N, Tipton KD (2010).
Increased protein intake reduces lean body mass loss during weight loss in
athletes. Med Sci Sports Exerc 42(2):326–337
3. Ina Garthe, Truls Raastad, Per Egil Refsnes, Anu Koivisto, and Jorunn
Sundgot-Borgen. Effect of Two Different Weight-Loss Rates on Body Composition
and Strength and Power-Related Performance in Elite Athletes. International Journal of Sport Nutrition and Exercise Metabolism, 2011, 97-104
4. Pasiakos SM, Cao JJ, Margolis LM, et al. Effects of
high-protein diets on fat-free mass and muscle protein synthesis following
weight loss: a randomized controlled trial. FASEB J. 2013;27:3837–47.
5. Brandon M. Kistler, Peter J. Fitschen, Sushant M. Ranadive, Bo
Fernhall, and Kenneth R. Wilund. Case Study: Natural Bodybuilding Contest
Preparation. International Journal of Sport Nutrition and Exercise Metabolism, 2014, 24,
694 -700
6. Lindy M. Rossow, David H. Fukuda, Christopher A. Fahs, Jeremy P.
Loenneke, and Jeffrey R. Stout. Natural Bodybuilding Competition Preparation and
Recovery: A 12-Month Case Study. International Journal of Sports Physiology and
Performance, 2013, 8, 582-592
7. Scott Lloyd Robinson1, Anneliese Lambeth-Mansell, Gavin Gillibrand,
Abbie Smith-Ryan and Laurent Bannock. A nutrition and
conditioning intervention for natural bodybuilding contest preparation: case
study. Journal
of the International Society of Sports Nutrition (2015) 12:20
