Related Experiment Video

Updated: Jul 10, 2025

Assessment of the Metabolic Effects of Isocaloric 2:1 Intermittent Fasting in Mice

Assessment of the Metabolic Effects of Isocaloric 2:1 Intermittent Fasting in Mice

Published on: November 27, 2019

Changes in energy and macronutrient intakes during Ramadan fasting: a systematic review, meta-analysis, and

Dana N Abdelrahim¹, Salah Eddine El Herrag^2,3, Meghit Boumediene Khaled^2,3

¹Research Institute of Medical and Health Sciences (RIMHS), University of Sharjah, Sharjah, United Arab Emirates.

Nutrition Reviews

|November 21, 2023

Abstract

Context:

Ramadan fasting (RF) is associated with various physiological and metabolic changes among fasting Muslims. However, it remains unclear whether these effects are attributable to changes in meal timing or changes in dietary energy and macronutrient intakes. Furthermore, the literature on the associations between RF, meal timing, and energy and macronutrient intakes is inconclusive.

Objectives:

This systematic review aimed to estimate the effect sizes of RF on energy and macronutrient intakes (carbohydrates, protein, fats, dietary fiber, and water) and determine the effect of different moderators on the examined outcomes.

Data Sources:

The Cochrane, CINAHL, EMBASE, EBSCOhost, Google Scholar, PubMed/MEDLINE, ProQuest Medical, Scopus, ScienceDirect, and Web of Science databases were searched from inception to January 31, 2022.

Data Extraction:

The studies that assessed energy, carbohydrate, protein, fat, fiber, and water intakes pre- and post-fasting were extracted.

Data Analysis:

Of the 4776 identified studies, 85 relevant studies (n = 4594 participants aged 9-85 y) were selected. The effect sizes for the studied variables were as follows: energy (number of studies [K] = 80, n = 3343 participants; mean difference [MD]: -142.45; 95% confidence interval [CI]: -215.19, -69.71), carbohydrates (K = 75, n = 3111; MD: -23.90; 95% CI: -36.42, -11.38), protein (K = 74, n = 3108; MD: -4.21; 95% CI: -7.34, -1.07), fats (K = 73, n = 3058; MD: -2.03; 95% CI: -5.73, 1.67), fiber (K = 16, n = 1198; MD: 0.47; 95% CI: -1.44, 2.39), and water (K = 17, n = 772; MD: -350.80; 95% CI: -618.09, 83.50). Subgroup analyses showed age significantly moderated the 6 dietary outcomes, and physical activity significantly moderated water intake. There were significant reductions in energy, carbohydrate, and protein intakes during RF.

Conclusions:

The change in meal timing rather than quantitative dietary intake may explain various physiological and health effects associated with RF.

Keywords:

caloric restriction chrononutrition dietary and lifestyle modification energy-yielding nutrient time-restricted eating

More Related Videos

Palatable Western-style Cafeteria Diet as a Reliable Method for Modeling Diet-induced Obesity in Rodents

Palatable Western-style Cafeteria Diet as a Reliable Method for Modeling Diet-induced Obesity in Rodents

Published on: November 1, 2019

Manipulation of Rhythmic Food Intake in Mice Using a Custom-Made Feeding System

Manipulation of Rhythmic Food Intake in Mice Using a Custom-Made Feeding System

Published on: December 16, 2022

Related Concept Videos

Metabolic States of the Body: Fasting and Starvation

Metabolic States of the Body: Fasting and Starvation

During the initial hours of fasting, the body uses up its glycogen stores as an energy source. Once these glycogen reserves are depleted, the body begins breaking down stored triglycerides and structural proteins. During this stage, glycerol becomes a key substrate for gluconeogenesis, while free fatty acids undergo beta-oxidation to provide energy for tissues, such as skeletal muscle. In the fasting state, the body spares protein breakdown as much as possible to conserve muscle and structural...

Metabolic States of the Body: The Postabsorptive State

Metabolic States of the Body: The Postabsorptive State

The postabsorptive state usually starts about four hours after a meal and lasts until the next meal is eaten. During this time, the digestive system stops absorbing nutrients, and the body uses stored energy reserves to maintain stable blood glucose levels.
Initially, glycogen stored in the liver is broken down to release glucose into the bloodstream, while glycogen in the muscles is broken down to supply glucose for energy directly within the muscle cells. As glycogen stores diminish,...

Metabolic States of the Body: The Absorptive State

Metabolic States of the Body: The Absorptive State

During the absorptive state, which lasts approximately four hours after a meal, the body absorbs nutrients from the gastrointestinal tract. The carbohydrates, proteins, and lipids we consume are broken down into monosaccharides, amino acids, and free fatty acids for absorption. While carbohydrates and proteins are absorbed as-is, lipids are absorbed in their broken-down forms and then re-esterified into triglycerides within enterocytes before being packaged into chylomicrons. These absorbed...

Regulation of Food Intake

Regulation of Food Intake

Short-term regulation of food intake primarily involves neural signals from the gastrointestinal (GI) tract, blood nutrient levels, and GI tract hormones. Communication between the gut and brain via vagal nerve fibers plays a significant role in evaluating the contents of the gut. Clinical studies have shown that protein ingestion produces a more prolonged response in these nerve fibers compared to an equivalent amount of glucose. Additionally, the activation of stretch receptors caused by GI...

Glucose Homeostasis: Regulation of Blood Glucose

Glucose Homeostasis: Regulation of Blood Glucose

Carbohydrates consumed through foods are converted into glucose, a crucial energy source for the body. In the prandial state, high blood glucose levels stimulate the secretion of insulin from the pancreas. Insulin inhibits hepatic glucose production and stimulates glucose uptake and metabolism by muscle and adipose tissue. The excess glucose is converted into glycogen and stored in the liver and muscles.
During fasting, when blood glucose levels are low, the pancreas secretes glucagon. it...

Energy Budgets

Energy Budgets

Organisms must balance energy intake with the energy required for growth, maintenance and reproduction. These trade-offs result in a variety of survivorship and reproductive strategies, including semelparity and iteroparity. Semelparous species, like annual plants, have only one reproductive episode in their lifetimes and consequently have short lifespans. Iteroparous species, by contrast, have many reproductive events during their lifetimes but have relatively few offspring. These two...

Articles linked to this work by shared authors, journal, and citation graph.

Effects of Three Consecutive Days of Diurnal Intermittent Fasting on Cognitive Function, Psychomotor Vigilance, and Sleep Quality in Adolescent Male Soccer Players: A Quasi-Experimental Parallel-Group Study.

Nutrients·2026

The Effects of Time-Restricted Eating in Women with Polyendocrine Metabolic Ovarian Syndrome: A Systematic Review and Meta-Analysis.

Nutrients·2026

Major depressive disorder attributed to intimate partner violence against women in North Africa and the Middle East: Global Burden of Disease Study.

Archives of women's mental health·2026

Use of dietetic services among pregnant women with gestational diabetes in the UAE: Prevalence, correlates, and patient experiences.

Women's health (London, England)·2026

Solution-Based Research to Address Disparities in Precision Cancer Health: A Case Report Elucidating the Design and Rationale of the Illinois Cancer Health Equity Research (I-CHER) Center.

International journal of environmental research and public health·2026

High risk of disordered eating is associated with body composition, behavioural factors, and perceived stress among university students: a cross-sectional study from the UAE.

Journal of nutritional science·2026

See all related articles