Effects of Calorie Restriction and Cold Stimuli on Health-related Indicators, Cognitive and Motor Functions

The goal of this clinical trial was to identify if duration of acute calorie restriction (CR)/fasting or combination CR with cold stimuli have any effects on mental and physical health-related markers, and to clarify if different fasting strategies have any effect on cognitive and motor functioning efficiency in different genders.

The main questions it aims to answer were:

* Does fasting duration have any effect on fasting evoked responses?
* Does cold interventions can modulate fasting evoked responses?
* Does sex have any effect on acute fasting evoked responses?

For the first part, participants were randomly classified into 4 groups: two experimental groups: 2-days of CR (0 kcal diet) and 6-days of CR (0 kcal diet), and two control groups: 2-days or 6-days usual diet. For the second part, participants were randomly assigned to undergo the following conditions: 2-days of CR with two 10-min whole-body cold-water immersions on separate days, 2-days of CR without cold-water immersion, 2-days without CR with two 10-min whole-body cold-water immersions on separate days, or 2-days of the usual diet without cold-water immersion in a randomized crossover fashion. Changes in anthropometric characteristics, perceived stress, metabolism, overall health (total blood count, sex hormones, etc.), psycho-emotional state, cognitive and motor functions were examined.

The goal of this clinical trial was to identify if duration of acute calorie restriction (CR)/fasting or combination CR with cold stimuli have any effects on mental and physical health-related markers, and to clarify if different fasting strategies have any effect on cognitive and motor functioning efficiency in different genders.

At first study part, participants were randomly classified into 4 groups: two experimental groups: 2-days of calorie restriction (CR) (0 kcal diet) and 6-days of CR (0 kcal diet), and two control groups: 2-days or 6-days usual diet. In the experimental groups, the participants were instructed to follow a prescribed zero-calorie diet with water provided ad libitum over a period of 2 or 6 days. In the control groups, the participants were instructed to maintain their previous eating habits for 2 or 6 days. Body weight and composition, heart rate variability, pulmonary gas exchange, blood pressure, and body temperature were assessed. Subsequently, participants completed self-assessment questionnaires, and then saliva samples were collected for further cortisol and sex hormones analysis, also capillary and venous blood samples were taken for ketone, glucose, insulin, lipid profile, catecholamines, brain-derived neurotrophic factor, total antioxidant capacity, malondialdehyde, glucagon, interleukin-10, metabolites of the kynurenines pathway and complete blood count concentrations evaluation. Then, the manual dexterity, and the cognitive and neuromuscular functions were assessed. The same measurements were repeated before each trial, after each trial and after 1 week.

At second part, participants were randomly assigned to undergo the following conditions: 2-days of CR with two 10-min whole-body cold-water immersions on separate days, 2-days of CR without cold-water immersion, 2-days without CR with two 10-min whole-body cold-water immersions on separate days, or 2-days of the usual diet without cold-water immersion in a randomized crossover fashion. The same measurements described in first part were repeated before each and after each condition.

Eligibility Criteria:
Inclusion criteria:

* body mass index 19.5-29.9 kg/m2,
* age 18-40 years,
* no excessive regular moderate or vigorous physical activity, i.e., ≥3 times per week,
* non-smokers,
* no medications that could affect the results of experiment,
* no history of any eating, oncological, metabolic, cardiovascular, skeletal, neuromuscular, pulmonary disorders or diseases, mental disabilities or conditions that could be worsened by exposure to acute cold (14°) water or fasting and affect experimental variables,
* no history of alcoholism or dependence on psychotropic drugs,
* no blood/needle phobia,
* no involvement in any temperature-manipulation program or extreme temperature exposure for ⩾3 months,

Exclusion criteria: smoking, were in a weight-reduction program, followed a low-carbohydrate diet.