The effect of meal frequency on body composition during 12-
weeks of strength training
Background: Human trials on the effect of meal frequency on body composition are
scarce. Short-term studies show increased rate of protein synthesis immediately after
intake of amino acids (Rennie 2002), and frequent meals are shown to aid in the
preservation of lean body mass when dieting (Iwao 1996). Consequently it could be
hypothesised that in response to strength training interventions, more frequent meals
will give larger muscle mass accumulation and lower fat mass than fewer meals.
Objective: The purpose of this study was to compare the effects of dividing the daily
food intake in 3 versus 6 meals per day on changes in body composition in young
men and women performing strength training over 12 weeks.
Design: Men (n=33) and women (n=15) aged 21 to 35 with at least one year of
previous strength training experience were matched according to strength and gender
and then randomly assigned to either a 6M group or a 3M group. The prescribed total
dietary intake was equal between the groups and was calculated to give a positive
energy balance of approximately 1200 KJ/day, a protein intake of 1.5-1.7 g/kg/day
and a carbohydrate intake of 5-7 g/kg/day (Table 1). During the training period the
dietary intake was controlled by repeated 24-hours recalls. All participants performed
the same periodized 2-split strength-training programme, training four times per
week, giving each muscle group one heavy session and one light session per week. In
the heavy sessions, training intensity varied between 10 and 3 RM sets, and 3-6 sets
were performed in each exercise. Project leaders, giving every participant the
necessary assistance, supervised all heavy sessions. Determination of body
composition was performed with DEXA at the beginning of, in the middle of and
immediately after the trial.
Results: A total of 16 men and 11 women completed the project. The 3M group had a
strong tendency towards greater gain in LBM than the 6M group after twelve weeks
of strength training, 1.71% {-0.18, 3.59}, p=0,075. After linear regression analysis
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the difference was significant when adjusted for gender and energy intake (p=0.045),
when adjusted for gender and protein intake (p=0.027), and when adjusted for gender,
protein intake, carbohydrate intake and fat intake (p=0.011). There were no
significant differences in change in fat mass between the groups, but a tendency
towards a greater gain in the 3M group, 7.33% {-5.23, 19.90}, p=0.241. The 3M
group had a 2.87% {0.62, 5.12} larger weight gain than the 6M group, p=0.014. Both
groups had significant increases in strength in all test exercises. The 3M group had a
larger strength gain in bench press, 10.85% {3.38, 18.32}, p=0.006 and triceps
pushdown, 12.81%, {3.14, 22.47}, p=0.011 and a larger strength gain for the upper
body, 8.37% {1.61, 15.13}, p=0.017 and total body, 6.28 {0.46, 12.09}, p=0.035 than
the 6M group. The participants had a 2.31% {0.83, 3.79}, gain in bone mineral
density of the spine during the twelve weeks of strength training, p=0.003, but there
were no differences between the groups.
Conclusion: In this study, three meals per day resulted in larger muscle- and strength
gain from strength training when in positive energy balance than six meals per day
over a period of twelve weeks. The reason why we draw opposite conclusions from
short-term studies needs further investigation. More long-term studies are needed to
determine the optimal meal frequency for ultimate gain in LBM from strength
training, and larger groups may be needed to determine an effect of meal frequency
on fat mass. The changes in fat mass had large variations within and between the
groups, making it difficult to draw any conclusions.
