STUDY DESIGN
EATHEALTHY
Brackground
In recent years, the prevalence of obesity in elderly persons has dramatically increased, with a consequent reduction in life expectancy and increased health problems.1Obesity is characterized by excessive body-fat accumulation, resulting in increased cerebral vascular disease risk; this increase in fat mass (FM) is usually accompanied by a decrease in fat-free mass (FFM) in elderly people.2–4Rosenberg defined this age-related decrease in muscle mass (MM) as sarcopenia.5
The presence of both conditions (obesity and sarcopenia) has been defined as sarcopenic obesity, characterized by reduced physical strength, a condition associated with increased disease risks.6Recent predictions indicate an increase in geriatric obesity; therefore, both aging and obesity may have a heavy impact on public health, increasing the cost of the health care system of Western countries.7
Aim
The study is aimed to evaluate body composition in obese aging patients and to determine the prevalence of sarcopenia in our population. We study the effects of a hypocaloric diet on body weight, lipid profile, glucose serum levels and blood pressure. Therefore, we are interested to evaluate the effectiveness of a diet rich in proteins in preventing the muscle mass loss. Moreover, we also investigate the microvascular impairments in hypertensive, hyperglycemic and hyperlipidemicobese aging subjects using noninvasive Laser Doppler Perfusion Monitoring(LDPM) technique, before and after diet treatment.
Matherial and Methods
Patients, aged between 65 and 85 years, with BMI > 30 kg/m2, attending the Outpatient Clinic of Clinical Medicine and Surgery Department, Federico II University and Hospital of Naples, Italy, are enrolled. Nutritional assessment is carried out by anthropometric measurements and bioelectrical impedance analysis, monthly performed until the end of the study (24 months). Biochemical parameters (glucose serum levels, cholesterol serum levels, high density lipoprotein serum levels, low density lipoprotein serum levels, triglycerides serum levels) and blood pressure are evaluated at the beginning and after 3, 6, 12, 15, 18, 21 and 24 months’ dieting. The exclusion criteria for the study are specific pathological conditions, such as kidney failure, systemic inflammatory disorders, cancer, neurodegenerative disorders, pharmacological treatment with steroids, antiretroviral drugs, weight-loss medications or insulin, and endocrine disorders. Hypocaloric diet with higher protein intake (1.2 g/Kg desirable body weight - DBW) is recommended to all patients.
Anthropometric measurements
Weight is measured to the nearest 1 g using a standard beam scale (Seca GmbH & Co KG, Hamburg, Germany). Height is measured using a wall-mounted stadiometer to the nearest 0.1 cm. Waist circumference (WC) is measured at the midpoint between the last rib and the iliac crest on the midaxillary line.8 Mid-upper-arm circumference is measured on the nondominant side at the midpoint between the tip of the acromial process of the scapula and the olecranon process of the ulna. Triceps skin-fold thickness is used to estimate MM according to the algorithm: (arm-muscle area [AMA] = [AC - {π × triceps skin fold}])2/4π. All measurements are performed at baseline and after 3, 6 and 12 months’ dieting, using standardized protocols.
Bioelectrical impedance analysis
To analyze fat and lean body mass, bioelectrical impedance analysis (BIA) is undertaken by tetrapolar BI (RJL 101; Akern SRL, Florence, Italy). BIA is performed with a single-frequency measurement (50 kHz). BIA with a single frequency provides the best information at a body level, because it minimizes frequency-dependent errors and variability of electric flow paths.9 For the analysis, Biatrodes (Akern), high-sensitivity tab electrodes, are used. FM and FFM are obtained from measures of resistance and reactance, using the algorithm provided by the manufacturer.
Muscle mass and obesity evaluation
MM is assessed using MM index (MMI) cutoff scores, defined as two MMI standard deviations below the mean of the adultreference group. In particular, MM is estimated from the resistance measured at 50 kHz (R50), according to the equation: MM =0.401× height2/R50 +3.825× sex -0.071× age +5.102.10 Height is in centimeters, R50 in ohms, age in years, and sex is coded 0 for women and 1 for men. The MMI is then calculated as: MM/height2 (kg/m2). Obesity is evaluated using established clinical and research cutoff scores for BMI, WC, FM%, and FMI. The cutoff scores for the classification of obesity include 1) BMI ≥ 30.0 kg/m2, 2) WC ≥ 102 cm in males and 88.0 cm in females, 3) FM% ≥ 35.0%, and 4) FMI ≥ 9.5 kg/m2.11
Handgrip-strength measurement
Handgrip is measured on the dominant and nondominant hands to the nearest kilogram using a hand dynamometer (78010; Lafayette Instrument Company, Lafayette, IN, USA). During measurement, the participant are in an upright position and the arm of the measured hand is unsupported and parallel to the body. The researchers follow a specific protocol for measurement of handgrip strength: in particular, the width of the dynamometer’s handle is adjusted to participants’ hand size, and then participants are instructed to exert maximal force. Therefore, for our study, three measurements are performed for the nondominanthand, and the average of recorded measurements is used for the analysis.
LDPM technique
Microvascular blood flow evaluation is performed on the patients in supine position in a quiet and temperature-controlled room (22 ± 23 °C). No subjects have any medication, food, alcohol and/or drinks containing caffeine 12 h prior to the blood flow measurement. Skin Blood Flow (SBF)is recorded using a laser Doppler perfusion monitoring apparatus (PeriFlux 4001 System, Perimed, Stockholm, Sweden) with the following characteristics: 780 nm wavelength, 10 Hz - 9 kHz bandwidth, 0.02 s time constant, 32 Hz sampling frequency. The LDPM apparatus is connected with a probe (PF 408, Perimed, Stockholm, Sweden), placed on the right forearm volar surface, and with a computer. After 10 min of acclimatization period, digital blood flow is recorded for 20 min by a Perisoft software. The mean value of SBF is expressed as arbitrary perfusion units (PU), while the power spectral density (PSD) of laser Doppler signals is reported as PU2/Hz. Finally, skin blood flow oscillations are analyzed by Wavelet transform12.
Post-occlusive reactive hyperemia is evaluated in all patients. After 20 min recording of microvascular blood flow under resting conditions, the brachial artery is occluded by a blood pressure cuff, placed at the right upper arm and inflated up to 50 mmHg above the systolic blood pressure. The blood pressure cuff is sudden deflated after 3 min brachial artery occlusion. Peak value (PK) is determined in PU as maximal perfusion value during hyperemia; percent increase of peak value (PK%) is calculated from the basal mean value; time to peak (Tp) is measured in seconds as the time from cuff release to the peak value; duration of hyperemia is evaluated in seconds as the time from cuff release up to the recovery of the mean value.
Spectral analysis: Microvascular blood flow oscillations, in the range: 0.005 to 2.0 Hz, are evaluated by Wavelet transform, a scale dependent method comprising an adjustable window length able to analyze both low and high frequencies12. Spectral analysis is performed on 20 min recordings under resting conditions, to obtain higher resolution of very low frequency components. Wavelet analysis, proposed by Morlet, permits to detect at least six frequency components in this interval, as reported by Stefanovska et al.13-14At first the overall spectral density of each frequency interval is determined; then the normalized spectral density for each frequency interval is evaluated as the ratio between the average spectral density of a specific frequency interval and the average total power spectral density. Therefore, the relative contribution of each frequency component is defined for the entire spectrum.
Diet treatment
To estimate usual nutrient intake, a food-frequency questionnaire (FFQ) is administered to all patients at the first visit. The questionnaire is used to measure participant’s usual food intake during the previous 3 months.
The caloric intake daily distribution is 20% of total calories in breakfast, 10% during each snack, 30% during lunch, and 30% during dinner. Obese older people are treated with 1.2 g/kg DBW/day of proteins (breakfast 25%–30% g, lunch 35%–40% g, dinner 35%–40% g).15-16
All patientsare instructed to change their diet, increasing protein intake. In particular, good sources of proteins low in fat, including lean meat, poultry, and fish, are recommended. For each patient, a personalized diet is prepared, and the amount of protein, carbohydrates, and lipids to ingest is calculated according to DBW. Dietary ingestion is estimated according to a daily food diary, self-administered, and three reports of nonconsecutive 24-hour recall every month during the follow-up.
Physical activity
According to previous data, physical activity is recommended in older peoples, at least five times a week for30 minutes (walking and/or aerobic activity); this activity is suggested to improve and maintain health.17-19 Physical activity is evaluated using the Italian version of the International Physical Activity Questionnaire – Short Form (IPAQ-SF).20 The questionnaire is administered to subjects at the first visit and at follow-up, performed monthly up to the end of the study.
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