Intermittent fasting does not affect whole-body glucose, lipid, or protein metabolism

Abstract

IF does not affect whole-body glucose, lipid, or protein metabolism in healthy lean men despite changes in muscle phosphorylation of GSK and mTOR. The decrease in resting energy expenditure after IF indicates the possibility of an increase in weight during IF when caloric intake is not adjusted. This study was registered at www.trialregister.nl as NTR1841.

Effects of intermittent fasting on glucose and lipid metabolism

“…Halberg et al (22) reported an increase (improvement) in insulin-mediated whole-body glucose uptake after 2 weeks in healthy men (BMI 25·7 (SD 0·4) kg/m 2 ). In contrast, Soeters et al (25) , the only group among these earlier studies to have used a (cross-over) controlled study design, found no change in insulin sensitivity in lean men following the same duration of time. In a 3-week study by Heilbronn et al (23) , which was conducted in a mixed sex healthy/overweight cohort, significant post-treatment reductions in postprandial insulin responses to a test-meal challenge was noted among male participants, whereas there was a contrasting decline in glucose tolerance among female participants (with no change in the insulinaemic response).…”

“…The majority of rodent studies (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) and a small number of human studies (22)(23)(24)(25)(26) have used IER protocols, which completely restrict energy intake (i.e. 100 % energy restriction) every other day, with fasting intervals ranging between 20 and 36 h. However, the long-term sustainability of this alternate day total fasting approach in human subjects is questionable due to the persistent hunger reported (24) .…”

“…Most recently, an 8-week pilot study completed by twenty-six obese male and female participants reported an average weight-loss of 9 %, accompanied by beneficial reductions in LDL-cholesterol and fasting TAG (26) . The earlier 2 (22,25) -3 (23,24) -week studies conducted in small groups (n ⩽ 16) of healthy and overweight participants were not originally designed as weight-loss studies, although participants on the 3-week study struggled to sustain prescribed energy intakes on feed days, and so incurred a modest weight-loss (24) . No post-treatment changes in fasting levels of insulin and glucose (when measured after a feed day) were observed by these (22,23,25) , whereas one study reported improved lipid profiles (24) .…”

Transcriptome analysis of peripheral blood mononuclear cells in human subjects following a 36 h fast provides evidence of effects on genes regulating inflammation, apoptosis and energy metabolism

“…Studies of individuals choosing to undergo periods of fasting for religious reasons have often provided conflicting findings, perhaps due to limited experimental control in these types of study, or because of inadequately long periods of fasting (Trepanowski et al 2011). Comparatively few studies of intermittent fasting have been performed with human subjects using well defined and controlled dietary interventions and, even in these cases, the findings are not always consistent (Heilbronn et al 2005a, b;Johnson et al 2007;Klempel et al 2012;Kroeger et al 2012;Soeters et al 2009). …”

The Effects of Intermittent Energy Restriction on Indices of Cardiometabolic Health

“…11 In recent years, intermittent energy restriction (IER) has become the subject of considerable scientific interest as an alternative approach to weight-loss and/or improving metabolic health, and has been studied in rodent and human populations. Most rodent trials [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] and preliminary trials in non-obese humans [31][32][33][34] have used total IER protocols in which energy intake is completely restricted on alternate days. However, debate regarding the maintainability of such an approach longterm led the authors of one of these first-inman trials to propose that the addition of one small meal on a "fasting" day may improve the long-term acceptability of IER.…”