Metabolic Effects of High Glycaemic Index Diets: A Systematic Review and Meta-Analysis of Feeding Studies in Mice and Rats

Abstract

Low glycaemic index (LGI) diets are often reported to benefit metabolic health, but the mechanism(s) responsible are not clear. This review aimed to systematically identify studies investigating metabolic effects of high glycaemic index (HGI) versus LGI diets in mice and rats. A meta-analysis was conducted to calculate an overall effect size, Hedge’s standardised mean differences (hereafter d), for each trait, with moderator variables considered in subsequent meta-regressions. Across 30 articles, a HGI diet increased five of the seven traits examined: body weight (d = 0.55; 95% confidence interval: 0.31, 0.79), fat mass (d = 1.08; 0.67, 1.49), fasting circulating insulin levels (d = 0.40; 0.09, 0.71), and glucose (d = 0.80; 0.35, 1.25) and insulin (d = 1.14; 0.50, 1.77) area under the curve during a glucose tolerance test. However, there was substantial heterogeneity among the effects for all traits and the small number of studies enabled only limited investigation of possible confounding factors. HGI diets favour body weight gain, increased adiposity and detrimentally affect parameters of glucose homeostasis in mice and rats, but these effects may not be a direct result of GI per se; rather they may be due to variation in other dietary constituents, such as dietary fibre, a factor which is known to reduce the GI of food and promote health via GI-independent mechanisms.

Tumour necrosis factor α induces neuroinflammation and insulin resistance in immortalised hypothalamic neurones through independent pathways

“…This is consistent with the increase in neuroinflammatory markers demonstrated previously by treatment with the saturated fatty acid palmitate and TNFα in neuronal cell lines, as well as the induction of cellular insulin resistance by palmitate . In vivo reports suggest differences in energy metabolism between rats and mice . Although differences between rat and mouse cell lines may be species‐dependent, disparity between the cell lines may also occur as a result of selection during subcloning.…”

“…10,29,30 In vivo reports suggest differences in energy metabolism between rats and mice. 31 Although differences between rat and mouse cell lines induced repression of signalling components such as IRS-1. 9,18,19,35,36 Furthermore, it should be considered that functional alterations to the IR itself have been reported in insulin resistance models, including phosphorylation of tyrosine residues 37 or lysosomal degradation.…”

Low‐Protein Diets with Fixed Carbohydrate Content Promote Hyperphagia and Sympathetically Mediated Increase in Energy Expenditure

“…Most studies assessing the effects of protein restriction on energy balance formulated isocaloric diets by substituting protein with carbohydrate, while keeping fat concentration constant;; whether the hyperphagic and metabolic responses to protein restriction are due to a reciprocal increase in carbohydrate content is largely unknown. In a recent meta‐analysis of 24 studies on rodents, diets high in carbohydrate but with adequate protein had no effect on calorie intake . In contrast, protein restriction was reported to increase calorie intake in rodents, regardless of carbohydrate or lipid content, in two studies .…”

Long-term sucrose solution consumption causes metabolic alterations and affects hepatic oxidative stress in wistar rats

“…Rats have stable energy metabolism, thus showing resistance to the development of full metabolic syndrome features with sucrose supplementation alone (Sun et al, 2018). In short, conflicting results are reported when fasting glucose alone is considered (Campbell et al, 2017). Hence, we conducted OGTT and ITT for an accurate assessment of the effects of sucrose solution consumption.…”