Acute Responses to Dietary Carbohydrate Manipulation

The Acute Responses to Manipulating Dietary Carbohydrate Content and Type on All Major Aspects of Energy Balance

Sugar is perceived negatively, leading to government taxation and targets to reduce consumption. These actions have been taken based on the limited evidence that high-sugar diets are associated with greater total energy intake. However, energy intake comprises just one half of the energy balance equation (e.g. balance = intake - expenditure). Without considering energy expenditure, it is impossible to understand the effects of sugar on health. Sugar, and perhaps total carbohydrate intake, may be important for energy balance - perhaps by stimulating increased energy expenditure.

Understanding dietary regulators of energy balance is more important than ever before, because diseases like obesity are a consequence of energy surplus (i.e. energy intake > energy expenditure). No studies have investigated a causal role of dietary sugar or carbohydrate on energy balance. The proposed research will seek to understand the acute (e.g. 24-hour) responses to manipulating dietary carbohydrate and sugar content on energy balance and health.

This research will contribute to enabling individuals to make informed dietary choices about carbohydrate and sugar consumption.

To achieve this, healthy non-obese adults will be recruited to a randomised crossover study. Measures of energy intake, energy expenditure, metabolic health, appetite, food preference, and gut microbiota will be taken. All laboratory trials will take place at the University of Bath.

Three diets will be investigated:

1. Control - reflecting the composition of a typical European diet
2. Low sugar - the same composition of a typical European diet but with <5% energy intake from sugar
3. Low carbohydrate - low carbohydrate diet with <5% energy intake from sugar and <8% energy intake from carbohydrate, replacing carbohydrate energy with fat

The study will consist of a 3-day lead-in period with the control diet followed by one trial day with each diet.

Study Overview

• Status: Completed
• Conditions: Nutrition and Energy Balance
• Intervention / Treatment: Other: Diet

Detailed Description

Dietary sugar is increasingly perceived in a negative way. This has led to taxation by government and guidelines by global public health bodies to reduce sugar intake to <5% of energy intake. All available public health guidelines regarding sugar advocate a reduction in sugar intake, despite a lack of evidence to support these recommendations. These guidelines focus on the association between sugar intake and energy intake, without regard for energy expenditure. This oversimplifies situations in which energy surplus is pathological, for example in diseases like obesity. This complexity is demonstrated by evidence that dietary sugar intake is decreasing in the United Kingdom, whilst rates of obesity have increased in the same timeframe.

It is important to consider energy expenditure in the context of health. The most variable component of energy expenditure between individuals is physical activity energy expenditure (PAEE), which varies from ~600-2100 kcal per day in men of a similar demographic. Current guidelines do not regard the effect that changing dietary sugar might have on PAEE and therefore total energy expenditure.

Carbohydrate availability dictates the capacity to perform physical work. However, the role of carbohydrate in regulating physical activity behaviours has only recently been considered. Ingestion of a carbohydrate-rich breakfast causes a significant increase in 24-hour PAEE compared with no breakfast consumption before midday. The magnitude of this difference is greatest prior to midday, near to when carbohydrate had been ingested and when glucose uptake to peripheral tissue is increased. This points towards a stimulatory role of carbohydrate or sugar on PAEE when carbohydrate is readily available to peripheral tissue. The amount of carbohydrate present in skeletal muscle is dictated by the amount of carbohydrate in the diet. As physical activity is performed by skeletal muscle, dietary carbohydrate intake may regulate physical activity behaviour. Consequently, reducing total carbohydrate intake may result in reduced PAEE.

Studies in which carbohydrate has been manipulated and physical activity has been measured have not been sufficient in answering this research question. Often self-report measures of physical activity are used, which are not sensitive enough to discern meaningful differences. Studies which have measured physical activity objectively, i.e. using pedometers or accelerometers, are confounded by a lack of information about actual carbohydrate intake or concurrent prescription of exercise interventions. Furthermore, government targets of reduced sugar intake to <5% of total energy intake are not aimed at overall carbohydrate intake per se. In the breakfast study mentioned, sugar intake was significantly greater amongst individuals who ate breakfast compared with individuals who fasted until midday. Therefore, it is also plausible that a regulatory role of carbohydrate on PAEE may be due to the type of carbohydrate rather than the absolute amount.

If the availability of carbohydrate to peripheral tissue plays a regulatory role on PAEE, then theoretically the effects of manipulating the amount or type of carbohydrate will be detectable acutely, within 24 hours.

• Study Type: Interventional
• Enrollment (Actual): 25
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • Bath, United Kingdom, BA2 7AY
    • Department for Health, University of Bath

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Body mass index 18.5-29.9 kg∙m-2
• Age 18-65 years
• Able and willing to provide informed consent and safely comply with study procedures
• Females to maintain record of regular menstrual cycle phase or contraceptive use
• No anticipated changes in diet/physical activity during the study (e.g. holidays or diet plans)

Exclusion Criteria:

• Any reported condition or behaviour deemed either to pose undue personal risk to the participant or introduce bias
• Any diagnosed metabolic disease (e.g. type 1 or type 2 diabetes)
• Any reported use of substances which may pose undue personal risk to the participants or introduce bias into the experiment
• Lifestyle not conforming to standard sleep-wake cycle (e.g. shift worker)
• Any reported recent (<6 months) change in body mass (± 3%)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: CONTROL; Diet consisting of 50% carbohydrate (20% sugar), 15% protein, 35% fat	Other: Diet; Macronutrient composition (specifically type and/or amount of carbohydrate) is manipulated
Experimental: LOW SUG; Diet consisting of 50% carbohydrate (<5% sugar), 15% protein, 35% fat	Other: Diet; Macronutrient composition (specifically type and/or amount of carbohydrate) is manipulated
Experimental: LOW CHO; Diet consisting of <8% carbohydrate (<5% sugar), 15% protein, >77% fat	Other: Diet; Macronutrient composition (specifically type and/or amount of carbohydrate) is manipulated

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
24-hour physical activity energy expenditure (kcal/day)	24-hour physical activity energy expenditure (kcal/day)	24 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
24-hour energy intake (kcal/day)	24-hour energy intake (kcal/day)	24 hours
Fasting glucose concentrations	Fasting glucose concentrations in serum samples	24 hours
Postprandial glucose concentrations	Postprandial glucose concentrations in serum samples	24 hours
Fasting insulin concentrations	Fasting insulin concentrations in serum samples	24 hours
Postprandial insulin concentrations	Postprandial insulin concentrations in serum samples	24 hours
Fasting triglyceride concentrations	Fasting and postprandial triglyceride concentrations determined in plasma samples	24 hours
Postprandial triglyceride concentrations	Postprandial triglyceride concentrations in serum samples	24 hours
Fasting non-esterified fatty acid concentrations	Fasting non-esterified fatty acid concentrations in serum samples	24 hours
Postprandial non-esterified fatty acid concentrations	Postprandial non-esterified fatty acid concentrations in serum samples	24 hours
Fasting beta-hydroxybutyrate concentrations	Fasting beta-hydroxybutyrate concentrations in serum samples	24 hours
Postprandial beta-hydroxybutyrate concentrations	Postprandial beta-hydroxybutyrate concentrations in serum samples	24 hours
Subjective appetite	Measured by 0-100 mm visual analogue scale	24 hours
Food preference ratings	Food preference ratings determined by bespoke computer software	24 hours
Resting substrate oxidation	Resting substrate oxidation determined by indirect calorimetry	24 hours
Postprandial substrate oxidation	Postprandial substrate oxidation determined by indirect calorimetry	24 hours
Palatability	Measured by 0-100 mm visual analogue scale	24 hours
Fasting cholesterol, HDL, and LDL concentrations	Fasting cholesterol, HDL, and LDL concentrations in serum samples	24 hours
Postprandial cholesterol, HDL, and LDL concentrations	Postprandial cholesterol, HDL, and LDL concentrations in serum samples	24 hours
Fasting leptin concentrations	Fasting leptin concentrations in serum samples	24 hours
Postprandial leptin concentrations	Postprandial leptin concentrations in serum samples	24 hours
Macronutrient intake	Macronutrient intake across 24-h	24 hours
Fasting FGF21 concentrations	Fasting FGF21 concentrations in serum samples	24 hours
Postprandial FGF21 concentrations	Postprandial FGF21 concentrations in serum samples	24 hours
Eating rate	Time taken to eat test meals	24 hours
Body mass	Body mass	24 hours
Waist and hip circumference	Waist and hip circumference, waist:hip ratio	24 hours
Fasting haematology profile	Fasting haematology profile including WBC, RBC, HGB, haematocrit, platelet count	24 hours

Collaborators and Investigators

• Sponsor: University of Bath

Publications and helpful links

General Publications

• Betts JA, Richardson JD, Chowdhury EA, Holman GD, Tsintzas K, Thompson D. The causal role of breakfast in energy balance and health: a randomized controlled trial in lean adults. Am J Clin Nutr. 2014 Aug;100(2):539-47. doi: 10.3945/ajcn.114.083402. Epub 2014 Jun 4.
• Smith HA, Gonzalez JT, Thompson D, Betts JA. Dietary carbohydrates, components of energy balance, and associated health outcomes. Nutr Rev. 2017 Oct 1;75(10):783-797. doi: 10.1093/nutrit/nux045.
• Erickson J, Sadeghirad B, Lytvyn L, Slavin J, Johnston BC. The Scientific Basis of Guideline Recommendations on Sugar Intake: A Systematic Review. Ann Intern Med. 2017 Feb 21;166(4):257-267. doi: 10.7326/M16-2020. Epub 2016 Dec 20.
• Hengist A, Davies RG, Rogers PJ, Brunstrom JM, van Loon LJC, Walhin JP, Thompson D, Koumanov F, Betts JA, Gonzalez JT. Restricting sugar or carbohydrate intake does not impact physical activity level or energy intake over 24 h despite changes in substrate use: a randomised crossover study in healthy men and women. Eur J Nutr. 2022 Nov 3. doi: 10.1007/s00394-022-03048-x. Online ahead of print.

Helpful Links

• SACN 2015 Report on Carbohydrates and Health

Study record dates

Study Major Dates

• Study Start (Actual): December 4, 2017
• Primary Completion (Actual): May 21, 2021
• Study Completion (Actual): May 21, 2021

Study Registration Dates

• First Submitted: April 9, 2018
• First Submitted That Met QC Criteria: April 25, 2018
• First Posted (Actual): April 26, 2018

Study Record Updates

• Last Update Posted (Actual): June 18, 2021
• Last Update Submitted That Met QC Criteria: June 16, 2021
• Last Verified: June 1, 2021

More Information

Terms related to this study

• Keywords: Nutrition; Carbohydrates
• Other Study ID Numbers: EP 17/18 87

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

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