Effects of a Ketogenic Diet on Psychological Outcomes


The aim of the study is to investigate how glycemia and ketonemia variations during three different diet protocols: a ketogenic diet without any restriction on calories intake (KD), a calorie-restricted ketogenic-mediterranean diet (KEMEPHY) and a calorie-restricted mediterranean diet (MD) affect appetite, executive functions and mood in overweight young women.

Full Title of Study: “Effects of Ketonemia and Glycemia Variations During Ketogenic and Mediterranean Weight Loss Diets on Appetite Levels, Executive Functions and Mood”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Basic Science
    • Masking: Double (Investigator, Outcomes Assessor)
  • Study Primary Completion Date: April 30, 2016

Detailed Description

Fifty overweight young women with a body mass index (BMI) greater than 25 will be randomly assigned to a ten days of ketogenic diet (KD), calorie-restricted ketogenic-mediterranean diet (KEMEPHY) or Mediterranean diet (MD). All subjects will begin the prescribed diet at the beginning of their follicular phase. Body composition, fasting blood glucose and β-hydroxybutyrate (BHB), visual analogue scale (VAS) to test appetite as well as psychological tests (one mood test and two cognitive tasks) will be obtained 5 days before the beginning and on the last day of the diet-period.


  • Other: Mediterranean diet
    • The group received a plan for a isocaloric Mediterranean Diet
  • Other: KEMEPHY
    • The group received a plan for a ketogenic mediterranean with herbal extracts diet
  • Other: KD
    • The group received a plan for a low carbohydrate ketogenic diet

Arms, Groups and Cohorts

  • Experimental: ketogenic-mediterranean diet with phytoextracts
    • The KEMEPHY diet (Paoli et al., 2011) is a mediterranean calorie-controlled ketogenic protocol (about 900 Kcal/day) with the use of some phytoextracts. During this protocol subjects are allowed to eat with no limits green leafy vegetables, cruciferous, zucchini, cucumbers and eggplants. The quantity of meat, eggs and fish was limited to once a day (120g of meat or 200g of fish or 1 egg). Moreover, subjects daily consumed four food supplements and liquid herbal extracts. Food supplements are high proteins (19g/portion) and very low carbohydrate (3.5g/portion) formulas simulating the aspect and taste of common carbohydrate rich foods added with dry phytoextracts (Lodi et al., 2016).
  • Active Comparator: Ketogenic Diet
    • The KD is a protocol in which all foods containing carbohydrate are excluded, whereas meat, eggs, fish, ham, green leafy vegetables, cruciferous, zucchini, cucumbers and eggplants can be eat without any limit. This protocol allows the use of oil, lemon juice (2 tbs/day), spices and aromatic herbs with a limitation of the use of saturated fats like butter, margarine and lard. Coffee, tea and herbal tea could be sweetened with sweeteners
  • Active Comparator: Mediterranean Diet
    • The MD is a balanced calorie-controlled diet. The calorie intake was 1200 Kcal/day of which 15% were proteins, 60% carbohydrates and 25% fat. In this protocol was highlighted the use of the typical ingredients of the mediterranean tradition, such as extravirgin olive oil, vegetables, fruits, fish, lean meat and whole grain cereals.

Clinical Trial Outcome Measures

Primary Measures

  • Motivation to eat and appetite
    • Time Frame: after 8 weeks
    • Motivation to eat and appetite were investigated by Visual Analog Scale (Hill & Blundell, 1982) , a test formed by 6 scales. Each scale was 10 cm long and was labelled with vertical lines and numbers (from 0 to10) every cm. Participants had to choose which part of the scale better described how they felt. The scale investigated appetite, fullness, desire to eat, how much would participant eat, urgency of eating and worries about food through 6 questions. Moreover, also the unfullness index (10 – fullness) was taken into account (R. J. Stubbs et al., 2000).
  • cognitive task1
    • Time Frame: after 8 weeks
    • The working memory test was an adapted version of the visuo-spatial N-back (Cui, Bray, Bryant, Glover, & Reiss, 2011; Haberecht et al., 2001). It consisted in remembering the position of the letter “o” that, in each trial, could appear in different positions, since a 9-part grid divides the screen. Number of correct or incorrect answers will be counted
  • Cognitive task2
    • Time Frame: after 8 weeks
    • The executive function test was an adapted version of the inhibitory control task (Amodio et al., 2010; Cona, Arcara, Amodio, Schiff, & Bisiacchi, 2013) . The stimulus were letters that appear in the centre of the screen. The task was formed by two main parts. In the first one the participant had to respond when the letter x or y appeared on the screen; in the second part the participant had to answer only when x preceded y and then vice versa. Number of correct or incorrect answers will be counted

Secondary Measures

  • body water content
    • Time Frame: after 8 weeks
    • Body composition will be assessed by body electrical impedance analysis (BIA) that measures Total body water and intra and extracellular water in liters
  • lean body mass
    • Time Frame: after 8 weeks
    • Body composition will be assessed by body electrical impedance analysis (BIA) that measures lean body mass in kg
  • fat body mass
    • Time Frame: after 8 weeks
    • Body composition will be assessed by body electrical impedance analysis (BIA) that measures fat body mass in kg
  • Mood
    • Time Frame: after 8 weeks
    • The mood test was the Italian Version of the Depression Anxiety Stress Scales-21. It was a self report measure formed by 21 items that reliably measure depression (lack of incentive, dysphoria and low self-esteem) as well as anxiety (somatic and subjective symptoms), stress (irritability, impatience, tension and arousal) and general distress (related to anxiety and depression) (Bottesi et al., 2015). The responses are given on a 4-point Likert scale, ranging from zero if “I strongly disagree” to 3 if “I totally agree”.
  • blood glucose
    • Time Frame: after 8 weeks
    • to assess diets’ effects on glycaemia, capillary blood will be analyzed. We measure glucose in mg/100ml
  • blood ketones
    • Time Frame: after 8 weeks
    • to assess diets’ effects on ketonemia, capillary blood will be analyzed. We measure ketone in mol/L

Participating in This Clinical Trial

Inclusion Criteria

  • female sex age between 20 and 35 years,
  • 25<BMI>39.9 kg/m2

Exclusion Criteria

  • smokers,
  • subjects under diet-treatment,
  • subjects treated for diseases such as diabetes,
  • cardiovascular diseases,
  • depression,
  • subjects doing sport more than 2 hours per week.

Gender Eligibility: Female

Minimum Age: 20 Years

Maximum Age: 35 Years

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • University of Padova
  • Provider of Information About this Clinical Study
    • Principal Investigator: Antonio Paoli, Professor – University of Padova
  • Overall Official(s)
    • Antonio Paoli, MD, Principal Investigator, University of Padova


Lodi A, Karsten B, Bosco G, Gómez-López M, Brandão PP, Bianco A, Paoli A. The Effects of Different High-Protein Low-Carbohydrates Proprietary Foods on Blood Sugar in Healthy Subjects. J Med Food. 2016 Nov;19(11):1085-1095. Epub 2016 Oct 18.

Paoli A, Bosco G, Camporesi EM, Mangar D. Ketosis, ketogenic diet and food intake control: a complex relationship. Front Psychol. 2015 Feb 2;6:27. doi: 10.3389/fpsyg.2015.00027. eCollection 2015. Review.

Paoli A. Ketogenic diet for obesity: friend or foe? Int J Environ Res Public Health. 2014 Feb 19;11(2):2092-107. doi: 10.3390/ijerph110202092. Review.

Paoli A, Bianco A, Grimaldi KA, Lodi A, Bosco G. Long term successful weight loss with a combination biphasic ketogenic Mediterranean diet and Mediterranean diet maintenance protocol. Nutrients. 2013 Dec 18;5(12):5205-17. doi: 10.3390/nu5125205.

Paoli A. Booster Ketones: Battling Hunger. Obesity (Silver Spring). 2018 Feb;26(2):252-253. doi: 10.1002/oby.22099. Epub 2018 Jan 10.

Stubbs BJ, Cox PJ, Evans RD, Cyranka M, Clarke K, de Wet H. A Ketone Ester Drink Lowers Human Ghrelin and Appetite. Obesity (Silver Spring). 2018 Feb;26(2):269-273. doi: 10.1002/oby.22051. Epub 2017 Nov 6.

Clinical trials entries are delivered from the US National Institutes of Health and are not reviewed separately by this site. Please see the identifier information above for retrieving further details from the government database.

At TrialBulletin.com, we keep tabs on over 200,000 clinical trials in the US and abroad, using medical data supplied directly by the US National Institutes of Health. Please see the About and Contact page for details.