BODY WEIGHT

Introduction

The body mass index relates body weight to height. Body mass index, or BMI, is defined as the weight in kilograms divided by the height in meters squared. Obesity is defined as a body mass index greater than 30 kg/m²; BMI between 25 kg/m² and 30 kg/m² defines overweight people, the normal weight being between 19 kg/m² and 25 kg/m². Obesity is a chronic disease with many important medical complications. The main cause of obesity is an imbalance between energy intake and energy expenditure.

The necessary treatment includes

• a calorie-restricted diet,
• increased physical activity, and
• nutritional modifications, with reduction of fat and sugar intake

The prevalence of obesity has increased in Western countries. It is a metabolic disease that predisposes to many medical complications such as cardiovascular disease, cancer, arthrosis, and diabetes, and it has also been implicated as a risk factor for chronic health conditions such as periodontitis. Obesity is associated with periodontal disease because the adipose tissues secrete some cytokines and hormones that are involved in inflammatory process. A high body mass index is associated with a systemic low-grade inflammatory state. Tumor necrosis factor-α, a proinflammatory cytokine, is produced in adipose tissues and is responsible for lowered insulin sensitivity, called insulin resistance which is responsible for elevated plasma glucose levels.

Periodontitis is characterized by alveolar bone loss, which is the consequence of bone resorption by the osteoclasts. Bone-forming cells (osteoblasts) and bone-resorbing cells (osteoclasts) are under hormonal control; the bone formation is negatively regulated by the hormone leptin, produced from adipocytes.

Health education should encourage better nutritional habits to reach normal weight and prevent obesity, and also to promote better oral hygiene to prevent periodontal disease (Alabdulkarim et al. 2005; Dalla Vecchia et al. 2005; Ekuni et al. 2008; Khader et al. 2009; Lalla et al. 2006; Linden et al. 2007; Nishida et al. 2005; Reeves et al. 2006; Saito et al. 2001; Saito et al. 2005; Wood, Johnson, and Streckfus 2003; Ylostalo et al. 2008).

Body Mass Index

High body mass index is a risk factor for periodontitis. There is a 16% increased risk for periodontitis per 1 kg/m² of increased body mass index. Body mass index is also significantly associated with the community periodontal index score (Ekuni et al. 2008). Total body weight is associated with periodontitis. Adolescents aged 17 to 21 years old have a 1.06 times increased risk for periodontal disease per 1 kg increase in body weight (Reeves et al. 2006). There is a significant correlation between body mass index and periodontitis, with a dose-response relationship (Nishida et al. 2005). Obesity is a risk factor for periodontitis; there is an association between high body weight and periodontal infection (Ylostalo et al. 2008). High body mass index is significantly associated with periodontitis, with an odds ratio of 2.9 (Khader et al. 2009). Obesity with a body mass index greater than 30 kg/m² is significantly associated with periodontitis, with an odds ratio of 1.77 (Linden et al. 2007).

Obese patients are 1.86 times more likely to present periodontitis according to the following groups:

• For patients older than 40 years of age, the odds ratio is 2.67.
• For females, the odds ratio is 3.14.
• For nonsmokers, the odds ratio is 3.36 (Alabdulkarim et al. 2005).

There is a positive correlation between body mass index and periodontitis, with a significantly higher prevalence in females. Obese females are significantly (2.1 times) more likely to have periodontitis (Dalla Vecchia et al. 2005). Obesity is also associated with deep probing pockets. High body mass index and body fat are significantly associated with the highest quintile of mean probing pocket depth (Saito 2005). There is a positive and significant association between high body mass index and the number of teeth with periodontal disease; this may be explained by obesity being responsible for a systemic low-grade inflammatory state (Lalla et al. 2006). People with higher categories of body mass index and upper body abdominal fat have a significantly increased risk of presenting with periodontitis (Saito et al. 2001).

There are significant correlations between body composition and periodontal disease. Body mass index and abdominal visceral fat are significantly associated with periodontitis (Wood, Johnson, and Streckfus 2003). Only 14% of normal-weight people have periodontitis; although 29.6% of overweight people and 51.9% of obese people present with periodontitis. High percentage of body fat, which is a person’s total fat divided by that person’s weight, is significantly associated with periodontal disease, with an odds ratio of 1.8 (Khader et al. 2009).

Physical Activity

There is an inverse linear association between sustained physical activity and periodontal disease: increased physical activity induces an improvement in insulin sensitivity and glucose metabolism. Periodontitis risk decreases with increased average physical activity. Compared with men in the lowest quintile for physical activity, those in the highest quintile have a significant 13% lower risk of periodontitis. Physically active patients present with significantly less average radiographic alveolar bone loss (Merchant et al. 2003).

Waist-to-Hip Ratio and Waist Circumference

High waist-to-hip ratio is a significant risk factor for periodontitis. Upper-body obesity as measured by the waist-to-hip ratio or the waist circumference is related to visceral abdominal adiposity. Because of induced systemic inflammation and insulin resistance by adipose tissue, it represents a risk factor for type 2 diabetes and cardiovascular diseases. Patients with a high waist-to-hip ratio present a significantly increased risk for periodontitis (Saito et al. 2001). Periodontitis is more frequent among patients with high waist circumference and high waist-to-hip ratio; high waist circumference is significantly associated with periodontitis with an odds ratio of 2.1 (Khader et al. 2009). Adolescents aged 17 to 21 years old have an 1.05 times increased risk of periodontal disease per 1-cm increase in waist circumference (Reeves et al. 2006). Waist-to-hip ratio, which characterizes abdominal visceral fat, is statistically significantly associated with periodontitis. There are significant correlations between body composition and periodontal disease, waist-to-hip ratio being the most significant element associated with periodontitis (Wood, Johnson, and Streckfus 2003). High waist-to-hip ratio is also significantly associated with the highest quintile of mean probing pocket depth (Saito et al. 2005).

Adipokines

Adipocytes produce cytokines, or adipokines, which are responsible for the association between obesity and other disease. Adipocytes in the adipose tissues of obese people produce large quantities of leptin, which regulates energy expenditure and body weight (Nishimura et al. 2003). Adiponectin and resistin are adipokines, which are responsible for systemic inflammation and insulin resistance in obese people. Serum resistin levels are higher in patients with periodontitis than in healthy subjects. Periodontitis patients with at least one tooth with a probing pocket depth greater than 6 mm have two times higher serum resistin levels than subjects without periodontitis (Furugen et al. 2008). Periodontitis is significantly associated with increased resistin levels. Resistin and adiponectin are secreted from adipocytes, and resistin plays an important role in inflammation (Saito et al. 2008).

Experimentation

Experimental calorie-restriction diet may have anti-inflammatory effects. A low-calorie diet results in a significant reduction in ligature-induced gingival index, bleeding on probing, probing depth, and attachment level. Periodontal destruction is significantly reduced in low-calorie-diet animals (Branch-Mays et al. 2008). After oral infection with Porphyromonas gingivalis, mice with diet-induced obesity present a significantly higher level of alveolar bone loss, with 40% increase in bone loss 10 days after inoculation. Accompanying the increase in bone loss, obese mice show an altered immune response with elevated bacterial counts for P. gingivalis (Amar et al. 2007).

The Metabolic Syndrome

Metabolic syndrome is characterized by the following:

• Central visceral obesity
• Hypertriglyceridemia and low levels of high-density lipoprotein cholesterol
• Hypertension
• Insulin resistance

Abdominal visceral obesity is characterized by an increased waist circumference.

Atherogenic dyslipidemia is defined by raised triglycerides and low concentrations of high-density lipoprotein cholesterol, elevated apolipoprotein B, small high-density lipoprotein cholesterol particles, and small low-density lipoprotein cholesterol particles.

Hypertension is characterized by chronic elevated blood pressure.

Insulin resistance or lowered insulin sensitivity is associated with high risk for cardiovascular disease and diabetes.

A proinflammatory state is generally present with the elevation of serum C-reactive protein because adipose tissues release inflammatory cytokines, inducing the elevation of C-reactive protein.

Prothrombotic state is characterized by raised serum plasminogen activator inhibitor and high fibrinogen (Grundy et al. 2004). The metabolic syndrome is associated with severe periodontitis; these patients are 2.31 times more likely to present with the metabolic syndrome. The prevalence of the metabolic syndrome is

• 18% among patients with no or mild periodontitis,
• 34% among patients with moderate periodontitis, and
• 37% among patients with severe periodontitis (D’Aiuto et al. 2008).

NUTRITION

Omega-3 Polyunsaturated Fatty Acids

Sources of omega-3 polyunsaturated fatty acids (eicosapentaenoic acid and docosahexaenoic acid) can be found in animals and especially in fish such as salmon, tuna, and mackerel. They are also present in many vegetables and nuts (alphalinolenic acid), such as walnuts and almonds. They are capable of reducing proinflammatory cytokine levels (Enwonwu and Ritchie 2007).

Fish oil rich in omega-3 polyunsaturated fatty acids, especially eicosapentaenoic acid and docosahexaenoic acid, may protect from />