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Trial registered on ANZCTR

Registration number

ACTRN12616001531404

Ethics application status

Approved

Date submitted

1/11/2016

Date registered

7/11/2016

Date last updated

7/11/2016

Type of registration

Retrospectively registered

Titles & IDs

Public title

Fasting and its effect on Cognitive Function

Scientific title

The effect of caloric restriction and fasting on cognitive performance, satiety levels and fatigue in healthy adult females

Secondary ID [1]

None

Universal Trial Number (UTN)

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Weight Loss

overweight / obesity

Cognitive function

Condition category

Condition code

Diet and Nutrition

Obesity

Mental Health

Studies of normal psychology, cognitive function and behaviour

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

In this randomised crossover design, adult women will complete three experimental days at the CSIRO Cognitive Laboratory in Adelaide, South Australia. Two days will utilise a Caloric Restriction Condition protocol. In both of these conditions, participants will consume a total of ~500 kcal throughout the testing. Two different patterns of delivery will permit the investigation of overall caloric restriction as well as meal timing on the relevant outcomes. In addition to their energy kcal allowance, participants are provided with ~100 kcal of caloric-neutral vegetable snacks (cucumber, celery & capsicum) for ad-lib consumption and to assist with any intestinal discomfort. The washout between each testing day is 1 week (7-days).

Bulking - Participants will consume a total allowance of ~500 kcal in the form of two liquid meal replacement shakes delivered at 9am and 11am respectively. Participants may only consume water throughout the day.

Extended Distribution - Participants will consume a total allowance of ~500 kcal in the form of one Liquid Meal Replacement at 9am, and two snack bars consumed at 12pm and 3pm respectively. Participants may only consume water throughout the day.

Intervention code [1]

Lifestyle

Intervention code [2]

Treatment: Other

Comparator / control treatment

Fasting - Participants will not be permitted to consume any kcal other than the ~100 kcal of caloric-neutral vegetable snacks (cucumber, celery & capsicum) for ad-lib consumption to assist with any intestinal discomfort. Participants may only consume water throughout the day.

Control group

Active

Outcomes

Primary outcome [1]

Cognitive Function: captured as mean performance on the CSIRO Computerised Fatigue Battery (CFB). The CFB consists of three tasks (Psychomotor Vigilance Task, Interference Task & Arithmetic Task) in each set, with three sets performed per assessment

Timepoint [1]

Baseline (0; 8:30am), +1.5, +3.5, +5.5, +7.5 hours

Primary outcome [2]

Cognitive Fatigue: captured as intra-individual variability estimates (e.g., Standard Deviation of Reaction Times, Coefficient of Variation of Reaction Times) during performance on the CSIRO Computerised Fatigue Battery (CFB). The CFB consists of three tasks (Psychomotor Vigilance Task, Interference Task & Arithmetic Task) in each set, with three sets performed per assessment

Timepoint [2]

Baseline (0; 8:30am), +1.5, +3.5, +5.5, +7.5 hours

Primary outcome [3]

Subjective Fatigue: Measured with a modified Activation-Deactivation Adjective Check List VAS instrument

Timepoint [3]

Baseline (0; 8:30am), +1.5, +3.5, +5.5, +7.5 hours

Secondary outcome [1]

Blood Glucose: Determined via use of a lancing device and blood glucose meter

Timepoint [1]

Baseline (0; 8:30am), +1.5, +2.5, +3.5, +4.5, +5.5, +6.5, +7.5 hours

Secondary outcome [2]

Satiety & Food Cravings Questionnaire

Timepoint [2]

Baseline (0; 8:30am), +1.5, +2.5, +3.5, +4.5, +5.5, +6.5, +7.5 hours

Eligibility

Key inclusion criteria

Self-reported cognitively healthy participants
Able to undertake a computerised battery
Not currently using a fasting regime for weight management or weight loss

Minimum age

20 Years

Maximum age

50 Years

Sex

Females

Can healthy volunteers participate?

Yes

Key exclusion criteria

Smoker
BMI >30
History of mood disorder (e.g., Depression or Anxiety)
Neurological Disease (e.g., Dementia)
Uncontrolled Hypertension
Diabetes (both types)
Lactose intolerant
Coeliac Disease
Nut/Seed allergy

Study design

Purpose of the study

Treatment

Allocation to intervention

Randomised controlled trial

Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)

Methods used to generate the sequence in which subjects will be randomised (sequence generation)

Masking / blinding

Who is / are masked / blinded?

Intervention assignment

Other design features

Phase

Type of endpoint/s

Statistical methods / analysis

Recruitment

Recruitment status

Active, not recruiting

Date of first participant enrolment

Anticipated

Actual

12/09/2016

Date of last participant enrolment

Anticipated

Actual

6/10/2016

Date of last data collection

Anticipated

11/11/2016

Actual

Sample size

Target

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

Funding & Sponsors

Funding source category [1]

Government body

Name [1]

CSIRO

Address [1]

Gate 13, Kintore Avenue, Adelaide, SA 5000

Country [1]

Australia

Primary sponsor type

Government body

Name

CSIRO

Address

Gate 13, Kintore Avenue, Adelaide, SA 5000

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

CSIRO Health and Medical Human Research Ethics Committee (CHM HREC) Low Risk Review Panel

Ethics committee address [1]

c/o Dr Anneliese Spinks
Ecosciences Precinct, 
41 Boggo Road, Dutton Park QLD 4102

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

29/08/2016

Approval date [1]

02/09/2016

Ethics approval number [1]

LR 16/2016

Summary

Brief summary

Fasting may have benefits for weight loss, the acute effects of this on cognitive function and mental fatigue throughout fasting days are not well understood. Some studies have shown negative impacts of fasting including slower psychomotor speed, slower reaction times, reduced memory capacity, reduced working memory function, and poorer inhibition and reasoning skills. These deficits have the potential to impact negatively on activities including driving, and functioning within the workforce more generally.  Ultimately these negative effects may impact on retention in these weight loss programs due to potentially unwanted side-effects, thus moderating their impact on health outcomes resulting from sustained weight loss.

A current trend in weight loss programs is to avoid true fasting days and instead, incorporate extreme Caloric Restriction days. One current approach, known as the 5:2 intermittent fasting method, recommends a total caloric intake allowance of ~2100kj/day (500 kcal) for women, and ~2500kj/day (600kcal) for men on two days out of every seven (i.e., two days per week).  Despite suggestions in the literature that intermittent fasting (including caloric restriction) improves metabolic markers in young women and in those with diabetes, to date, little is known about the impact of caloric restriction on cognitive function, fatigue and satiety. In particular, there has been limited exploration about how best to distribute the permissible restricted calories across the day. The timing of energy consumption is likely an important factor that could alter any potentially negative effects of caloric restriction on cognitive function and fatigue, particularly in the context of carbohydrates.  

This study will explore the impact of different nutrient intake timing during caloric restriction days on cognitive performance, fatigue, satiety and blood glucose.  

In light of literature showing negative effects of fasting on cognitive function, our hypotheses are as follows:
1) Fasting will result in poorer cognitive function and enhanced fatigue compared to both of the caloric restriction arms (Bulking and Extended Distribution)
2) Extended Distribution of calories will result in less fatigue throughout the afternoon assessments compared to Bulking
3) Fasting will lead to significantly higher subjective ratings of fatigue and satiety compared to both caloric restriction conditions
4) Fasting will result in significantly lower blood glucose readings compared to both caloric restriction conditions

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

Dr Ian Zajac

Address

CSIRO, PO Box 10041, Adelaide BC, SA, 5000

Country

Australia

Phone

+61 8 8303 8875

Fax

[email protected]

Contact person for public queries

Name

Ian Zajac

Address

CSIRO, PO Box 10041, Adelaide BC, SA, 5000

Country

Australia

Phone

+61 8 8303 8875

Fax

[email protected]

Contact person for scientific queries

Name

Ian Zajac

Address

CSIRO, PO Box 10041, Adelaide BC, SA, 5000

Country

Australia

Phone

+61 8 8303 8875

Fax

[email protected]

No information has been provided regarding IPD availability

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

Source	Title	Year of Publication	DOI
Embase	Modified fasting compared to true fasting improves blood glucose levels and subjective experiences of hunger, food cravings and mental fatigue, but not cognitive function: Results of an acute randomised cross-over trial.	2021	https://dx.doi.org/10.3390/nu13010065

N.B. These documents automatically identified may not have been verified by the study sponsor.

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