What is the Maximum Amount of Carbohydrates That is Still Able to Induce Ketosis and Suppress Appetite?

Ketosis and Appetite Suppression - What is the Maximum Carbohydrate Intake That is Still Associated With Appetite Suppression in a Low Energy Diet?

Two dietary approaches, very low energy diets (VLEDs) and ketogenic low carbohydrate diets (KLCDs), have the ability to suppress appetite. The suppression of appetite typically observed during these diets is believed (but not clinically proven) to be due to ketosis, a condition where circulating concentrations of ketone bodies are increased due to a higher production of ketones in the liver. Little is known about the potential mechanisms through which ketosis may lead to appetite suppression in VLEDs and KLCDs. A 'ketogenic diet' typically contains less than 50 grams carbohydrate per day, yet ketosis has been seen in subjects who consume diets with a carbohydrates ranging between 59-192 grams per day. Although an association between ketosis and appetite suppression has been established, the minimum level of ketosis and maximum carbohydrate intake that is still associated with appetite suppression remains unknown and should be explored. The ability to increase carbohydrate intake while maintaining a suppressed appetite will allow dieters to consume more carbohydrate-rich food that is beneficial for health without feeling more hungry.

The study, 'can Appetite Suppression be achieved using KEtogenic Diets with more carbohydrates?' (ASKED) aimed to:

• to identify the maximum carbohydrate intake that is still associated with appetite suppression in a low energy diet and to determine the impact of a higher carbohydrate intake on appetite suppression, ketosis, body composition, and resting metabolic rate. A
• to evaluate the impact of weight loss while in and out of ketosis on markers of appetite (appetite related hormones and appetite sensations measured using visual analogue scales).

Study Overview

• Status: Completed
• Conditions: Obesity
• Intervention / Treatment: Other: Low energy diet 70 gram carbohydrates; Other: Low energy diet 100 gram carbohydrates; Other: Low energy diet 130 gram carbohydrates

Detailed Description

A total of 101 healthy, weight stable (< 2 kg variation in BW within the last 3 months), adult (18-65 years old) individuals with obesity (body mass index [BMI] 30-45 kg/m2) who were not actively trying to lose weight were recruited through advertisements in Facebook, Twitter and the intranet of St. Olavs Hospital and the Norwegian University of Science and Technology (NTNU) in Trondheim, Norway from May 2017 - August 2018.

Informed consent was obtained from all participants before enrollment in the study, and participants were allowed to withdraw at any time.

Study participants were randomized to one of three intervention arms: low, medium, or high CHO groups. Computer-generated randomization was performed using a block sampling (fixed block size) and stratification approach to account for the potential confounding factors of sex and BMI (< 35 and ≥ 35 kg/m2). (34, 35). Study participants were not made aware of which intervention arm they were allocated to until the end of the trial. All participants underwent an 8-week, supervised LED containing different amounts of CHO, followed by 4 weeks of gradual refeeding and weight stabilization. Measurements were taken before diet initiation (baseline), at the end of the WL phase (week 8) and at the end of the weight stabilization phase (week 12) to allow for the evaluation of the impact of WL in or out of ketosis on appetite markers.

• Study Type: Interventional
• Enrollment (Actual): 100
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Norway
  • Trondheim, Norway
    • St Olavs Hospital

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• class I or II obesity (BMI 30-45 kg/m2)
• weight stable (<2 kg variation in weight within the last 3 months)
• not currently dieting to lose weight
• women who are either post-menopausal, taking oral contraceptives or with a normal cycle (28 ± 2 days)

Exclusion Criteria:

• pregnant
• breast-feeding
• drug or alcohol abuse within the last two years
• currently taking medication known to affect appetite or induce weight loss
• enrolled in another obesity treatment program
• history of psychological disorders
• having had bariatric surgery
• metabolic diseases (such as hypo/hyperthyroidism and diabetes type 1 or 2)
• eating disorders
• lactose intolerance
• gastrointestinal (particularly cholelithiasis), kidney, liver, lung, cardiovascular disease
• malignancies

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Low energy diet 70 gram carbohydrates; isocaloric 4128 kilojoules/day (1000 kilocalories/day) for men and women, low energy diet containing 70 gram carbohydrates for 8 weeks.	Other: Low energy diet 70 gram carbohydrates; isocaloric 4128 kilojoules/day (1000 kilocalories/day) for men and women, low energy diet containing 70 gram carbohydrates
Experimental: Low energy diet 100 gram carbohydrates; isocaloric (4128 kilojoules/day (1000 kilocalories/day) for men and women, low energy diet containing 100 gram carbohydrates for 8 weeks.	Other: Low energy diet 100 gram carbohydrates; isocaloric 4128 kilojoules/day (1000 kilocalories/day) for men and women
Experimental: Low energy diet 130 gram carbohydrates; isocaloric 4128 kilojoules/day (1000 kilocalories/day) for men and women, low energy diet containing 130 gram carbohydrates for 8 weeks.	Other: Low energy diet 130 gram carbohydrates; isocaloric 4128 kilojoules/day (1000 kilocalories/day) for men and women, low energy diet containing 130 gram carbohydrates

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Suppression of appetite sensations measured using online visual analogue scales	Assessed by an online version of Visual Analogue Scale (VAS), a validated scale used to measure appetite sensations in response to questions posed regarding feelings of hunger, fullness, desire to eat, prospective consumption. Study participants are asked questions such as 'How hungry do you feel right now?' and are asked to provide a response by marking across a 100 millimeter long line with sentences anchored at each end such as "I have never been more hungry/ or I am not hungry at all" corresponding to their feeling. VAS measurements are done in fasting, immediately after a meal and every 30 minutes for 2.5 hours. Measurements are quantified by measuring the distance from the left end of the line to the mark indicated by the participant.	12 weeks (at start of study (baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period)
Suppression of appetite indicated by appetite-related hormones Active Ghrelin, Total Glucagon Like Peptide-1, Total Peptide YY and Insulin	Measurement of plasma samples of appetite related hormones: Active ghrelin (AG), Total Glucagon Like Peptide-1 (Total GLP-1), Total Peptide YY (Total PYY) and Insulin measured in fasting, immediately after a meal and every 30 minutes for a period of 2.5 hours. Blood samples are first collected in Ethylenediaminetetraacetic acid (EDTA) tubes (72 milliliters in total) and centrifuged for 10 minutes at 18 degrees celsius with 3200 revolutions per minute (RPM). Plasma samples are then stored in -80 degree celsius freezer until analysis using a Metabolic Hormone Magnetic Bead Panel (Lincoplex Kit, Merck Millipore, USA). Results of plasma samples of these hormones will be presented in picograms (pg) per milliliter (ml).	12 weeks (at start of study (baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period)
Suppression of appetite indicated by appetite-related hormone Cholecystokinin (CCK)	Measurement of plasma samples of appetite related hormone Cholecystokinin (CCK) measured in fasting, immediately after a meal and every 30 minutes for a period of 2.5 hours. Blood samples are first collected in Ethylenediaminetetraacetic acid (EDTA) tubes (72 milliliters in total inclusive of blood collected for analysis of hormones listed above) and centrifuged for 10 minutes at 18 degrees celsius with 3200 revolutions per minute (RPM). Plasma samples are then stored in -80 degree celsius freezer until they are sent to the University of Copenhagen to be analyzed by the research group of Professor Jens F Rehfeld using his 'In-house Radioimmunoassay method'. The results of plasma CCK will be presented in picomoles (pmol) per liter (l).	12 weeks (at start of study (baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period)
Ketosis	Measured with beta hydroxybutyrate (BHB), a ketone body and indicator of ketosis in plasma form. Fasting blood samples are first collected in Ethylenediaminetetraacetic acid (EDTA) tubes (inclusive of the 72 milliliters of blood collected for analysis of appetite hormones listed above) and centrifuged for 10 minutes at 18 degrees celsius with 3200 revolutions per minute (RPM). Plasma samples are then stored in -80 degree celsius freezer until analysis using a Ketone Body Assay (MAK-134, Merck Millipore, USA). The results of plasma BHB will be presented in millimoles (mmol) per liter (l).	12 weeks (at start of study (baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body composition (air displacement plethysmography)	Body composition measured with air displacement plethysmography (BodPod, COSMED, Italy). The output of the measurement of body composition using air displacement plethysmography provides absolute values in kilograms for body weight, fat mass and fat free mass.	12 weeks (at start of study (baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period)
Percent fat/fat-free mass (air displacement plethysmography)	Percent fat mass and fat free mass is measured with air displacement plethysmography (BodPod, COSMED, Italy). The output of the measurement of body composition using air displacement plethysmography provides fat mass and fat free mass as a percentage of total body weight.	12 weeks (at start of study (baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period)
Body composition (bioelectrical impedance)	Body composition measured using bioelectrical impedance analysis (BIA, Biospace, Korea). The output of the measurement of body composition using bioelectrical impedance analysis provides absolute values in kilograms for body weight, fat mass and fat free mass.	12 weeks (at start of study (baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period)
Percent fat/fat-free mass (bioelectrical impedance analysis)	Percent fat mass and fat free mass is measured with bioelectrical impedance analysis (BIA, Biospace, Korea). The output of the measurement of body composition using bioelectrical impedance analysis provides fat mass and fat free mass as a percentage of total body weight.	12 weeks (at start of study (baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period)
Intracellular and extracellular water measured using Bioelectrical impedance analysis	Intracellular and extracellular water is measured with bioelectrical impedance analysis (BIA, Biospace, Korea). The output of the measurement of body composition using bioelectrical impedance analysis provides information on the amount total body water (made up of intracellular and extracellular water) in liters.	12 weeks (at start of study (baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period)
Waist and hip circumference	Waist and hip circumference will be measured with a measuring tape and the results will be provided in centimeters.	12 weeks (at start of study (baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period)
Height	Height of the participant will be measured with a stadiometer and will be provided in meters.	12 weeks (at start of study (Baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period)
Body mass index (BMI)	Body mass index (BMI) will be calculated using the measurements of body weight (obtained using the weight in kilograms output provided by bioelectrical impedance analysis) and height in meters measured using the stadiometer using the following formula: (kilograms/meters)^2	12 weeks (at start of study (Baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period)
Resting metabolic rate	Measured through indirect calorimetry. Indirect calorimetry is a technique that measures oxygen consumption and carbon dioxide production during rest to estimate resting metabolic rate. Results will be presented in kilocalories per day.	12 weeks (at start of study (Baseline), at week 9 (after diet induced weight loss period), and week 13 (after weight stabilization period)

Collaborators and Investigators

• Sponsor: Norwegian University of Science and Technology
• Investigators: Study Chair: Magne Børset, phd prof, Norwegian University of Science and Technology

Publications and helpful links

General Publications

• Martins C, Roekenes J, Salamati S, Gower BA, Hunter GR. Metabolic adaptation is an illusion, only present when participants are in negative energy balance. Am J Clin Nutr. 2020 Nov 11;112(5):1212-1218. doi: 10.1093/ajcn/nqaa220.
• Martins C, Roekenes J, Hunter GR, Gower BA. Association between ketosis and metabolic adaptation at the level of resting metabolic rate. Clin Nutr. 2021 Aug;40(8):4824-4829. doi: 10.1016/j.clnu.2021.06.029. Epub 2021 Jul 6.
• Deemer SE, Plaisance EP, Martins C. Impact of ketosis on appetite regulation-a review. Nutr Res. 2020 May;77:1-11. doi: 10.1016/j.nutres.2020.02.010. Epub 2020 Feb 20.
• Martins C, Roekenes J, Gower BA, Hunter GR. Metabolic adaptation is associated with less weight and fat mass loss in response to low-energy diets. Nutr Metab (Lond). 2021 Jun 11;18(1):60. doi: 10.1186/s12986-021-00587-8.
• Martins C, Nymo S, Aukan MI, Roekenes JA, Coutinho SR, Hunter GR, Gower BA. Association between ss-Hydroxybutyrate Plasma Concentrations after Hypocaloric Ketogenic Diets and Changes in Body Composition. J Nutr. 2023 Jul;153(7):1944-1949. doi: 10.1016/j.tjnut.2023.05.010. Epub 2023 May 12.
• Martins C, Roekenes J, Salamati S, Gower BA, Hunter GR. Reply to E Ravussin and L Redman. Am J Clin Nutr. 2020 Dec 10;112(6):1655-1656. doi: 10.1093/ajcn/nqaa309. No abstract available.

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2017
• Primary Completion (Actual): December 31, 2019
• Study Completion (Actual): December 31, 2019

Study Registration Dates

• First Submitted: October 21, 2016
• First Submitted That Met QC Criteria: October 21, 2016
• First Posted (Estimated): October 25, 2016

Study Record Updates

• Last Update Posted (Actual): October 4, 2023
• Last Update Submitted That Met QC Criteria: October 2, 2023
• Last Verified: October 1, 2023

More Information

Terms related to this study

• Keywords: Weight Loss; Ketogenic Diet; Ketosis; Caloric Restriction; Hunger; Appetite Regulation; Diet, Reducing
• Additional Relevant MeSH Terms: Metabolic Diseases; Acid-Base Imbalance; Acidosis; Ketosis
• Other Study ID Numbers: 2016/1297

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