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P. 41
NAFLD and interactions with insulin resistance
EXCESSIVE BODY WEIGHT AND RISK OF NASH: ARE
ALL OBESE PATIENTS EQUAL?
Amalia Gastaldelli
Cardiometabolic Risk Unit,
Institute of Clinical Physiology - CNR,
Pisa, Italy
Email: amalia@ifc.cnr.it
Take home messages
• Excessive BMI is not synonymous with excessive fat and vice-versa.
• Visceral, more than subcutaneous, fat is associated with NAFLD and hepatic insulin resistance.
• Ectopic fat is usually not limited to one organ (i.e., the liver) and for this reason subjects with
NAFLD have increased cardiometabolic risk.
• Adipose tissue insulin resistance is one of the main causes of ectopic fat in the liver.
• Adipose tissue insulin resistance is associated with lipotoxicity, production of ROS and cell damage.
• Saturated fats are more lipotoxic than unsaturated fats.
Introduction
Although obesity is one of the major risk factors for NAFLD and NASH, these two conditions may be
present in non-obese subjects [1, 2].Visceral fat accumulation, rather than generalized obesity, is linked
to NAFLD and to MetS in general [1].Thus, in assessing the risk or presence of NAFLD it is important
to assess if a subject is obese and also to quantify fat deposition.
Assessment of obesity and fat distribution
The previous syllabus covered the definition of BMI and its limitations. In view of these limitations,
a direct, more accurate measurement of fat mass should be performed (e.g. DEXA, air-displacement
plethysmography, bioimpedance or body scanning procedures) [3].
Even in subjects with BMI <30 kg/m2, total adipose tissue can be up to 50% of body weight with
the majority of fat accumulated as subcutaneous adipose tissue (SAT), but with accumulation also as
visceral adipose tissue (VAT) (up to 10 kg or 30% of total fat) and intrathoracic fat (up to 0.5 kg) [4].
Intrathoracic fat includes mediastinal or extrapericardial fat and epicardial fat [34].Waist circumference
is a good indicator of visceral fat accumulation, although imaging techniques, such as magnetic resonance
imaging or computed tomography should be used to accurately quantify abdominal fat [4]. On the other
hand, the presence of epicardial fat can also be diagnosed by ultrasonography [4].
The International Liver Congress™ 2015 • Vienna, Austria • April 22–23, 2015 41
EXCESSIVE BODY WEIGHT AND RISK OF NASH: ARE
ALL OBESE PATIENTS EQUAL?
Amalia Gastaldelli
Cardiometabolic Risk Unit,
Institute of Clinical Physiology - CNR,
Pisa, Italy
Email: amalia@ifc.cnr.it
Take home messages
• Excessive BMI is not synonymous with excessive fat and vice-versa.
• Visceral, more than subcutaneous, fat is associated with NAFLD and hepatic insulin resistance.
• Ectopic fat is usually not limited to one organ (i.e., the liver) and for this reason subjects with
NAFLD have increased cardiometabolic risk.
• Adipose tissue insulin resistance is one of the main causes of ectopic fat in the liver.
• Adipose tissue insulin resistance is associated with lipotoxicity, production of ROS and cell damage.
• Saturated fats are more lipotoxic than unsaturated fats.
Introduction
Although obesity is one of the major risk factors for NAFLD and NASH, these two conditions may be
present in non-obese subjects [1, 2].Visceral fat accumulation, rather than generalized obesity, is linked
to NAFLD and to MetS in general [1].Thus, in assessing the risk or presence of NAFLD it is important
to assess if a subject is obese and also to quantify fat deposition.
Assessment of obesity and fat distribution
The previous syllabus covered the definition of BMI and its limitations. In view of these limitations,
a direct, more accurate measurement of fat mass should be performed (e.g. DEXA, air-displacement
plethysmography, bioimpedance or body scanning procedures) [3].
Even in subjects with BMI <30 kg/m2, total adipose tissue can be up to 50% of body weight with
the majority of fat accumulated as subcutaneous adipose tissue (SAT), but with accumulation also as
visceral adipose tissue (VAT) (up to 10 kg or 30% of total fat) and intrathoracic fat (up to 0.5 kg) [4].
Intrathoracic fat includes mediastinal or extrapericardial fat and epicardial fat [34].Waist circumference
is a good indicator of visceral fat accumulation, although imaging techniques, such as magnetic resonance
imaging or computed tomography should be used to accurately quantify abdominal fat [4]. On the other
hand, the presence of epicardial fat can also be diagnosed by ultrasonography [4].
The International Liver Congress™ 2015 • Vienna, Austria • April 22–23, 2015 41
