FYI, this paper is being reviewed over on the Leangains/Intermittent Fasting (IF) site as supportive of IF.
do you know how significant the fat free mass lost was?
As with any review -- there are some limitations due to the flaws in the underlying studies used. For example, the underlying studies reviewed used different techniques to measure fat mass -- which could be a source of variation. The paper does a nice job of pointing out these limitations. At least someone is looking at it. I believe this paper is referencing another paper that looked at primarily alternate day fasting (something like, eat 25% of baseline calories on fasting day, and then eat 100-110%% of baseline calories on feeding day). I don't think I could do that.
However, there were multiple "intermittent fasting" papers referenced, but not described in as much detail (I did not read those.) Also note, training was not examined or taken into account. The paper uses the term "fat free mass" as a synonym for "lean body mass." I found that modestly confusing
CR = calorie restriction
Three quotes from the paper that I found interesting:
"When an individual loses weight by
dietary restriction alone, approximately 75% of weight
is lost as fat mass, and 25% of weight is lost as fat free
"Similar to what was reported for daily CR,
short-term trials (4 to 12 weeks) of intermittent CR
decreased fat mass by 11 to 16%, and fat free mass by
1 to 4% from baseline (21 thru 23). To date, there are no
moderate-term trials (13 to 24 weeks) of intermittent
CR, so no comparisons between diets could be made for
longer intervention periods."
After 8 to 12
weeks of treatment, 11 to 16% reductions in fat mass
were reported for intermittent restriction (21 thru 23), while
10 to 20% decreases were demonstrated for daily restriction
(8 thru 12). These two diets differed, however, in their effects
on lean mass. For instance, a lower proportion of lean mass
was lost in response to intermittent CR (90% weight lost as
fat, 10% weight loss as fat free mass) (21 thru 23) when compared
to daily CR (75% weight lost as fat, 25% weight loss
as fat free mass) (4, 7 thru 16). Therefore, intermittent CR may
be a more effective diet for the retention of lean mass when
compared to daily CR.