The appropriate rate of weight loss
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People often judge the success of weight loss by how fast the scale drops. There are many issues with this approach, aggressive dieting, rigidity, adherence and therefore sustainability issues, long-term success etc; but what impact does your rate of weight loss have on your body.
You lose weight with the intention of losing fat. Not all weight loss is fat loss. The rate at which you lose weight can impact the source of this weight loss (fat mass or fat-free mass). Fat-free mass or Lean body mass (LBM) is the tissues that make up our body weight (Muscle, Bone, Skin, Blood, Organs) excluding fat mass.
The aim of dieting is to maximise fat loss and minimise muscle loss. There have been numerous studies investigating the effects our rate of weight loss has on strength, fat and muscle loss.
The aim of dieting is to maximise fat loss and minimise muscle loss.
Garthe et al, 2011, compared a slow reduction (SR) of weight loss 0.7% of bodyweight/week vs. 1.4% fast reduction (FR) weight-loss approach. They studied the effects on LBM and strength over a 4 to 12-week period. SR group increased LBM by 2.1%, fat mass loss was 31% compared to FR group’s LBM didn’t change and their fat loss was 21%. The SR improved on all strength tests during this trial and FR did not with the exception of 1RM squat.
The SR group lost more fat mass and increased LBM
Mero et al 2010, Compared 0.5kg loss/week to 1kg loss/week (-550Kcal/-1100Kcal respectively) over a 4-week period. They discovered the 1kg group had ~30% reduction in testosterone levels and a 5% decrease in bench press strength.
The 1kg group had greater reductions in testosterone and strength performance
Helms et al, 2014 advised that tissue loss during a diet is influenced by the size of the deficit (and therefore rate of weight loss). The faster your rate of weight loss, the more LBM you lose. A recommendation of 0.5-1% bodyweight per week has been suggested to optimise muscle retention when dieting; gradual weight loss is superior for muscle retention.
1% bodyweight is the recommended upper limit rate of weight loss/week. Some sources argue this is too high with an upper limit of 0.8%/week.
Based on research, an appropriate rate of weight loss is 0.5-1% of bodyweight per week to minimise muscle and strength loss.
This may not seem like much i.e an 80kg person losing 0.5% bodyweight per week (~0.4kg / ~0.8lb), but it can be assumed this loss is predominantly from fat mass.
The gradual approach enables a lesser deficit, more flexibility, better adherence, consistency and overall sustainability.
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