Effects of Ketogenic Diet on Body Composition and Performance in Soccer Players

Overview

A ketogenic diet (KD) is a nutritional approach, usually adopted for weight loss, that restricts daily carbohydrates under 30 g/day. KD showed contradictory results on sport performance, whilst no data are available on team sports. The investigators will investigate the influence of a KD on different parameters in soccer players

Full Title of Study: “Effects of a Very Low Carbohydrate Ketogenic Diet on Body Composition, Muscle Strength, Muscle Area, Metabolism and Performance in Semi-professional Soccer Players”

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: October 30, 2018

Detailed Description

Sixteen semi-professional soccer players will be randomly assigned to a ketogenic diet (KD n=8) or to a western diet (WD n=8). Diets contain the same amount of protein (1.8g/Kg body weight/day). Body weight and body composition will be measured by dual energy x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA). Resting energy expenditure (REE), respiratory exchange ratio (RER), cross sectional area (CSA) and isometric muscle strength of quadriceps, counter movement jump (CMJ) and yoyo intermittent recovery test will be measured.

Interventions

  • Other: Western diet
    • Subjects in this intervention will follow a normal western diet
  • Other: ketogenic diet
    • Subjects in this group will follow a low carbohydrate ketogenic diet

Arms, Groups and Cohorts

  • Experimental: Ketogenic diet
    • Ketogenic diet: less than 30 g/day of carbohydrate. Subjects can eat beef, veal, poultry, fish, raw and cooked vegetables without restriction, cold cuts such as dried beef, eggs and seasoned cheese (parmesan), ketogenic pasta (selected with a ketogenic ratio of 4:1), fruits with the lowest glycemic index (blueberry, raspberry), raw nuts and seeds, ghee butter, plant oils and fats from avocado, coconut and olives
  • Active Comparator: Western diet
    • The western diet (WD) is composed mainly of whole cereals (spelt, rye, oat) and pseudo-cereals (buckwheat, quinoa, amaranth), whole grain pasta, potatoes, meet, fish, vegetables, fruit, legumes, olive oil, milk and red wine (at most 1 glass per day). It ensure a constant energy and macronutrient balance: protein 1.8g x Kg-1 x body weight-1 x day-1, (30%), fats 20-25% and carbohydrate 50-55%.

Clinical Trial Outcome Measures

Primary Measures

  • Fat body mass
    • Time Frame: 4 weeks
    • Body composition with DEXA: we measure body fat mass in grams.
  • lean body mass
    • Time Frame: 4 weeks
    • Body composition with DEXA: we measure lean body mass in grams.
  • Visceral Adipose tissue (VAT)
    • Time Frame: 4 weeks
    • Body composition with DEXA: VAT in grams
  • Total body water
    • Time Frame: 4 weeks
    • We will use a BIA to calculate totally body water and intracellular and extracellular water in liters

Secondary Measures

  • resting energy expenditure (REE)
    • Time Frame: 4 weeks
    • Measured through gas analyzer in ml/02/kg min
  • respiratory ratio (RR)
    • Time Frame: 4 weeks
    • Measured through gas analyses (ratio between CO2 and O2)
  • specific performance
    • Time Frame: 4 weeks
    • Yoyo intermittent recovery test level 1: in seconds
  • lower limb power
    • Time Frame: 4 weeks
    • squat jump test: height of the jump in cm
  • quadriceps muscle area
    • Time Frame: 4 weeks
    • muscle area measured in cm2 through ultrasound
  • quadriceps muscle thickness
    • Time Frame: 4 weeks
    • muscle thickness measured cm through ultrasound
  • quadriceps strength
    • Time Frame: 4 weeks
    • isometric contraction measured in N, the normalized per muscle area (N x cm2)
  • quadriceps strength per area
    • Time Frame: 4 weeks
    • the strength of isometric contraction (outcome 10) normalized per muscle area (Outcome 7). Expressed as (N x cm2)

Participating in This Clinical Trial

Inclusion Criteria

  • semiprofessional soccer players – male Exclusion Criteria:

  • body fat percentage over 32%, (determined via dual energy X-ray absorptiometry DEXA), – cardiovascular, – respiratory, gastrointestinal, – thyroid or any other metabolic diseases, – weight change more than 2 Kg over the last month, – adherence to special diets, – use of nutritional supplements (except a daily multivitamin-mineral) – use of medication to control blood lipids or glucose and goal-keepers.

Gender Eligibility: Male

Minimum Age: 18 Years

Maximum Age: 30 Years

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

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

References

Rubini A, Bosco G, Lodi A, Cenci L, Parmagnani A, Grimaldi K, Zhongjin Y, Paoli A. Erratum to: Effects of Twenty Days of the Ketogenic Diet on Metabolic and Respiratory Parameters in Healthy Subjects. Lung. 2017 Feb;195(1):155. doi: 10.1007/s00408-016-9958-0. No abstract available.

Paoli A, Bianco A, Grimaldi KA. The Ketogenic Diet and Sport: A Possible Marriage? Exerc Sport Sci Rev. 2015 Jul;43(3):153-62. doi: 10.1249/JES.0000000000000050.

Paoli A, Grimaldi K, D'Agostino D, Cenci L, Moro T, Bianco A, Palma A. Ketogenic diet does not affect strength performance in elite artistic gymnasts. J Int Soc Sports Nutr. 2012 Jul 26;9(1):34. doi: 10.1186/1550-2783-9-34.

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