Postprandial Metabolic and Appetite Responses to Different Food Intake Sequences in Athletes

Emerging evidence suggests that following a 'carbohydrate-last meal pattern', wherein foods rich in protein, fat, fiber, and/or polyphenols are consumed before sources of simple carbohydrate (CHO) in a meal, results in reduced postprandial glycaemic responses than the reverse food order or a co-ingestion pattern. This effect has been observed across the spectrum of glucose tolerance, from patients with diabetes to individuals with normal glucose tolerance (Kuwata et al., 2016; Nishino et al., 2018; Lu et al., 2019; Sun et al., 2020). Furthermore, reduced glucose excursions have been linked to decreased subsequent hunger and energy intake (Lu et al., 2019; Wyatt et al., 2021).

However, to date, no studies on food intake sequence have targeted athletes, despite their increased CHO demands (Thomas et al., 2016) which could expose them to repeated episodes of hyperglycaemia and high glycaemic variability, known to increase the risk of adverse cardiovascular outcomes and all-cause mortality (Loader et al., 2015; Cavero-Redondo et al., 2017; Faerch et al., 2018). Additionally, athletes often face pressure to meet body composition standards and may benefit from strategies that enhance satiety and craving control. Finally, there is reason to believe that better glycaemic control could lead to improved performance, given that enhancements in endurance activities have been observed with a low-glycemic-index diet compared to a high-glycemic-index diet (Heung-Sang Wong et al., 2017).

Therefore, this randomised crossover trial is part of a wider project which seeks to explore the impact of food intake sequence on metabolic health and performance in athletes. Specifically, this trial aims to investigate the acute, postprandial metabolic and appetite responses to consuming an identical meal in two intake sequences (CHO-last versus CHO-first) in athletes, while in the resting state.

Study Overview

• Status: Not yet recruiting
• Conditions: Healthy; Craving; Postprandial Hyperglycemia; Nutrition, Healthy; Hunger
• Intervention / Treatment: Other: Carbohydrate-last meal pattern; Other: Carbohydrate-first meal pattern

Detailed Description

Participants will be required to visit the research facilities at Cidade do Futebol (Portugal Football School's headquarters) on three separate occasions, following a 10-12-hour overnight fast and abstaining from alcohol consumption and strenuous physical activity the day before (e.g. no exercise causing sweating or heavy breathing). Visits will be separated by a wash-out period of 7 days to ensure participants experience similar dietary and physical activity patterns in the 24 hours preceding the trials. Each visit is expected to last approximately 4 hours.

In the screening and familiarisation visit, athletes will be asked to provide written informed consent to participate in the study and answer a series of questions to confirm their eligibility and safety for enrolment. Subsequently, an anthropometric assessment, blood pressure measurement, fasted blood collection and 2-hour 75-g oral glucose tolerance test (OGTT) will be performed to establish participants' baseline characteristics and analyse biochemical markers of the glucose and lipid metabolism to identify any further exclusion criteria (i.e., glycated haemoglobin (HbA1c); glucose; insulin; triglycerides; total, high-density lipoprotein and low-density lipoprotein cholesterol; haemogram and high-sensitivity C-reactive protein). To familiarise participants with the cannulation procedure ahead of the experimental trials, a trained and experienced nurse will insert a cannula (a small plastic tube) into a vein on the participants' arm, from which fasting and 2-h OGTT blood samples will be drawn (15 ml in total).

Eligible participants will be instructed to monitor their diet and physical activity for 24 hours before their first experimental visit and replicate these patterns before the second experimental visit.

In both experimental visits, participants will arrive at the research facilities between 8:00-9:00 and rest comfortably for 10 minutes. Body mass and blood pressure will be remeasured. Then, cannulation will be performed, and 18.5 ml venous blood samples will be drawn immediately before and at 30, 60, 90, 120, and 180 minutes after the meal challenge to assess postprandial changes in insulin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), ghrelin, peptide YY (PYY), triglycerides, and non-esterified fatty acids (NEFA) concentrations. At similar timepoints, as well as at 15 and 45 minutes, capillary blood glucose will be measured using a finger prick glucometer, and appetite ratings will be marked by the athletes on 100-mm visual analogue scales.

Upon completing the research assessments, participants will be asked to photograph and record the timing, type, and amounts of foods, drinks, and/or supplements consumed for an additional 3 hours to evaluate their prospective, ad libitum intake.

• Study Type: Interventional
• Enrollment (Estimated): 15
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Rita Giro; Phone Number: +351 912748205; Email: up201307940@edu.fcna.up.pt
• Study Contact Backup: Name: João Brito, PhD; Email: joao.brito@fpf.pt

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Adult (18-64 years old)
• Male
• Trained (meeting training and performance caliber criteria ≥Tier 2; McKay et al., 2022)
• Healthy (meeting the exclusion criteria for medical conditions)
• Normal glucose tolerant according to the latest criteria established by the American Diabetes Association (ElSayed et al., 2023): HbA1c <5.7%, fasting plasma glucose <5.6 mmol/L (100 mg/dL) and 2-h plasma glucose <7.8 mmol/L (140 mg/dL) during a 75-g OGTT
• Able and willing to provide informed consent and safely comply with study procedures

Exclusion Criteria:

• Any medical condition or behaviour deemed either to pose undue personal risk to the participant or introduce bias into the experiment (e.g. anaemia and other haematological disorders; alcohol or substance abuse; any condition affecting the glucose and lipid metabolism or appetite, reviewed on a case by case basis)
• Any reported medication or supplementation that may interfere with the glucose metabolism (e.g., acarbose, insulin, metformin, semaglutide, thiazolidinediones, sulfonylureas, corticosteroids, thiazide diuretics); lipid metabolism (e.g., statins, nicotinic acid, colestyramine anhydrous, ezetimibe, fibrates, L-carnitine); or appetite (e.g., metoclopramide, carbamazepine, phenobarbital, phenytoin, primidone). Other medication and supplementation will be reviewed on a case by case basis.
• Known food allergy, intolerance or hypersensitivity to any of the test-meal ingredients
• Recent change in body mass (± 2 kg in the last 2 months)
• Smoking
• Having donated more than 400 ml of blood within 3 months of the screening visit or more than 1500ml of blood in the previous 12 months

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: CL - CF; The interventions (carbohydrate-last meal pattern (CL) or carbohydrate-first meal pattern (CF)) will be delivered in random order at two study visits, separated by a wash-out period of 7 days. If participants are allocated to this study arm, they will receive the CL on the first visit and the CF on the second visit. The nutritional composition of the test-meal will comply to the current sports nutrition guidelines for the pre-exercise meal (i.e., 1-4 g of CHO/kg of body mass, moderate amounts of protein, low-fat and fibre content, 5-10 mL/kg of body mass of fluids) (Thomas et al., 2016). Participants will be encouraged to consume the meal in full within 15 minutes, at a comfortable pace, to mimic real eating circumstances.	Other: Carbohydrate-last meal pattern; Skyr yoghurt, whey protein and almonds over ~5 min, immediately followed by white bread, strawberry jam, banana and pulp-free orange juice over ~10 min.; Other Names: CL; CHO-last; Other: Carbohydrate-first meal pattern; White bread, strawberry jam, banana and pulp-free orange juice over ~10 min, immediately followed by skyr yoghurt, whey protein and almonds over ~5 min.; Other Names: CF; CHO-first
Active Comparator: CF - CL; The interventions (carbohydrate-last meal pattern (CL) or carbohydrate-first meal pattern (CF)) will be delivered in random order at two study visits, separated by a wash-out period of 7 days. If participants are allocated to this study arm, they will receive the CF on the first visit and the CL on the second visit. The test-meal will be identical and isocaloric in both interventions of the study.	Other: Carbohydrate-last meal pattern; Skyr yoghurt, whey protein and almonds over ~5 min, immediately followed by white bread, strawberry jam, banana and pulp-free orange juice over ~10 min.; Other Names: CL; CHO-last; Other: Carbohydrate-first meal pattern; White bread, strawberry jam, banana and pulp-free orange juice over ~10 min, immediately followed by skyr yoghurt, whey protein and almonds over ~5 min.; Other Names: CF; CHO-first

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postprandial blood glucose concentrations	Difference between food intake sequences in the incremental area under the curve 0-120 and 0-180 min; peak concentrations (mmol/L); time-to-peak (min); and change from baseline data (mmol/L) of capillary blood glucose measured by a validated glucometer	Baseline and 15, 30, 45, 60, 90, 120, 180 minutes following the test meal

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postprandial subjective appetite ratings	Difference between food intake sequences in the total area under the curve 0-180 min; peak/nadir rating (mm); time-to-peak/nadir (min); and change from baseline data (mm) of appetite ratings measured by validated 100-mm visual analogue scales (Flint et al, 2000)	Baseline and 15, 30, 45, 60, 90, 120, 180 minutes following the test meal
Prospective ad libitum energy intake	Difference between food intake sequences in the total energy (kcal) consumed within 3 hours from the end of the experimental visit, assessed by a photography-supported dietary record of foods and fluids	0-3 hours post-trial
Prospective ad libitum nutritional intake	Difference between food intake sequences in the total carbohydrate, protein and fat (grams; g/kg of body mass and % of total energy intake) consumed within 3 hours from the end of the experimental visit, assessed by a photography-supported dietary record of foods and fluids	0-3 hours post-trial
Postprandial serum insulin concentrations	Difference between food intake sequences in the incremental area under the curve 0-120 and 0-180 min; peak concentrations (microIU/ml); time-to-peak (min); and change from baseline data (microIU/ml) of serum insulin measured by a chemiluminescent immunoassay	Baseline and 30, 60, 90, 120, 180 minutes following the test meal
Postprandial plasma total GLP-1 concentrations	Difference between food intake sequences in the incremental area under the curve 0-120 and 0-180 min; peak concentrations (pg/ml); time-to-peak (min); and change from baseline data (pg/ml) of plasma GLP-1 measured by a total GLP-1 ELISA kit	Baseline and 30, 60, 90, 120, 180 minutes following the test meal
Postprandial plasma total GIP concentrations	Difference between food intake sequences in the incremental area under the curve 0-120 and 0-180 min; peak concentrations (pg/ml); time-to-peak (min); and change from baseline data (pg/ml) of plasma GIP measured by a total GIP ELISA kit	Baseline and 30, 60, 90, 120, 180 minutes following the test meal
Postprandial serum total ghrelin concentrations	Difference between food intake sequences in the total area under the curve 0-120 and 0-180 min; nadir concentrations (pg/ml); time-to-nadir (min); and change from baseline data (pg/ml) of serum ghrelin measured by a total ghrelin ELISA kit	Baseline and 30, 60, 90, 120, 180 minutes following the test meal
Postprandial plasma total PYY concentrations	Difference between food intake sequences in the incremental area under the curve 0-120 and 0-180 min; peak concentrations (pg/ml); time-to-peak (min); and change from baseline data (pg/ml) of plasma PYY measured by a total PYY ELISA kit	Baseline and 30, 60, 90, 120, 180 minutes following the test meal
Postprandial serum triglyceride concentrations	Difference between food intake sequences in the incremental area under the curve 0-180 min; peak concentrations (mmol/L); time-to-peak (min); and change from baseline data (mmol/L) of serum triglycerides measured by the GPO/POD method	Baseline and 30, 60, 90, 120, 180 minutes following the test meal
Postprandial serum NEFA concentrations	Difference between food intake sequences in the total area under the curve 0-180 min; nadir concentrations (mmol/L); time-to-nadir (min); and change from baseline data (mmol/L) of serum NEFA measured by an enzymatic colorimetric assay	Baseline and 30, 60, 90, 120, 180 minutes following the test meal

Collaborators and Investigators

• Sponsor: Universidade do Porto
• Collaborators: Fundação para a Ciência e a Tecnologia; Federação Portuguesa de Futebol
• Investigators: Principal Investigator: Rita Giro, FCNAUP, University of Porto; Portugal Football School, Federação Portuguesa de Futebol

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2024
• Primary Completion (Estimated): September 1, 2024
• Study Completion (Estimated): October 1, 2024

Study Registration Dates

• First Submitted: April 9, 2024
• First Submitted That Met QC Criteria: April 9, 2024
• First Posted (Estimated): April 15, 2024

Study Record Updates

• Last Update Posted (Estimated): April 15, 2024
• Last Update Submitted That Met QC Criteria: April 9, 2024
• Last Verified: February 1, 2024

More Information

Terms related to this study

• Keywords: lipid metabolism; satiety; glucose metabolism; food order; meal sequence; sport nutrition
• Additional Relevant MeSH Terms: Glucose Metabolism Disorders; Metabolic Diseases; Hyperglycemia
• Other Study ID Numbers: FOODSEQ-MARS

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No