What management strategies are recommended for individuals who are metabolically obese but of normal weight?

Management of Metabolically Obese Normal Weight (MONW) Individuals

Individuals with metabolically obese normal weight phenotype should be treated with the same comprehensive lifestyle interventions used for metabolically unhealthy obesity, focusing on a 500-750 kcal/day caloric deficit, ≥150 minutes/week of moderate-intensity aerobic exercise, and behavioral therapy, despite their normal BMI. 1, 2

Understanding the MONW Phenotype

MONW individuals carry multiple cardiometabolic risk factors despite normal weight (BMI <25 kg/m²), characterized by excess visceral adipose tissue, ectopic fat deposition, adipose tissue inflammation, and reduced skeletal muscle mass. 3 The prevalence ranges from 5-45% depending on diagnostic criteria and population studied. 3

• These individuals face substantially elevated cardiovascular risk compared to metabolically healthy normal-weight persons, with a 1.80-fold increased risk of developing metabolic abnormalities. 4
• The primary determinants include genetic background, lifestyle factors, visceral adiposity, and low cardiorespiratory fitness rather than total body weight. 5

Core Treatment Strategy: Comprehensive Lifestyle Intervention

Dietary Intervention

Implement a structured dietary program creating a 500-750 kcal/day energy deficit, regardless of normal BMI status. 1

• For women, prescribe 1,200-1,500 kcal/day; for men, 1,500-1,800 kcal/day. 1, 2
• Focus on low-energy density foods including fruits, vegetables, whole grains, and high-fiber foods, following the DASH eating plan pattern. 1, 2
• Reduce portion sizes and limit high-fat, high-sodium foods to decrease visceral adiposity. 1
• The macronutrient composition should be balanced and healthy, with adequate protein, vitamins, and minerals. 1, 6

Physical Activity Prescription

Prescribe ≥150 minutes/week of moderate-intensity aerobic activity (such as brisk walking), distributed across most days of the week. 1, 2

• Add resistance training 2-3 times per week to improve skeletal muscle mass and metabolic function, which are typically reduced in MONW individuals. 6, 2, 3
• For long-term maintenance, increase physical activity to 200-300 minutes/week. 1
• Target ≥10,000 steps daily to address the low cardiorespiratory fitness characteristic of MONW. 2
• Physical inactivity is strongly associated with metabolic syndrome even in normal-weight individuals (OR 3.73), making exercise non-negotiable. 7

Behavioral Therapy Component

Enroll in an intensive multicomponent behavioral program with ≥14 sessions over 6 months, delivered by trained interventionists. 1, 2

• Implement regular self-monitoring of food intake, physical activity, and body weight (weekly or more frequently). 1
• Provide structured behavior change support through individual or group sessions. 1
• Assess and address barriers including motivation, major life stresses, psychiatric illness, and medication review for weight-promoting drugs. 1

Treatment Duration and Follow-up

The initial intensive intervention should last 6-12 months with frequent (initially weekly) contact. 1

• After the initial phase, maintain regular contact at least monthly for a minimum of one year to prevent metabolic deterioration. 1, 6
• Schedule follow-up ideally every 4-6 weeks to support lifestyle changes and monitor metabolic parameters. 6, 2

Metabolic Risk Management

Screen for and independently manage obesity-related complications including fasting glucose, HbA1c, blood pressure, liver function, and sleep apnea. 1, 2

• Target blood pressure <120/80 mmHg through weight control, sodium restriction, and DASH dietary pattern. 2
• For elevated LDL-C, target <100 mg/dL through lifestyle initially; consider statin therapy if LDL remains >100 mg/dL after 3 months of lifestyle intervention. 2
• Review and optimize medications, replacing weight-promoting drugs with weight-neutral or weight-reducing alternatives when possible. 1
• Avoid betablockers as first-line antihypertensive agents in MONW individuals, as they are associated with metabolic syndrome (OR 2.63). 7

Expected Outcomes and Goals

Target a 5-10% reduction in body weight over 6 months, even though baseline BMI is normal, to reduce visceral adiposity and improve metabolic parameters. 1

• A 5-10% weight loss can improve systolic BP by 3 mmHg, diastolic by 2 mmHg, and decrease HbA1c by 0.6-1.0% if prediabetes is present. 2
• The primary goal is preventing or treating metabolic complications rather than achieving a specific weight target. 1
• Approximately 49% of metabolically healthy individuals will develop metabolic abnormalities within 10 years without intervention, making early aggressive lifestyle modification critical. 4

Pharmacotherapy Considerations

Currently, there are no specialized pharmacologic treatments specifically for MONW; if metabolic complications warrant intervention, use the same therapies as for metabolically unhealthy obesity. 5

• Consider anti-obesity medications (semaglutide, tirzepatide, phentermine-topiramate ER, liraglutide) if metabolic complications are severe, though evidence specifically in MONW is limited. 2
• The decision for pharmacotherapy should be based on the presence and severity of metabolic complications rather than BMI alone. 2

Critical Pitfalls to Avoid

Do not dismiss metabolic risk based on normal BMI appearance—this delays necessary interventions and allows progression to overt metabolic disease. 3

• Do not assume MONW individuals need less aggressive intervention than obese individuals with metabolic dysfunction; the lifestyle intervention intensity should be identical. 1, 4
• Avoid focusing solely on weight loss as the outcome measure; prioritize improvement in metabolic parameters, visceral adiposity, and cardiorespiratory fitness. 3, 5
• Do not neglect resistance training—it is essential for addressing the reduced skeletal muscle mass characteristic of MONW. 6, 3

Multidisciplinary Approach

Treatment should be delivered by a multidisciplinary team including trained primary care professionals, nutrition specialists, and exercise physiologists. 1, 6

• Comprehensive programs administered by multiprofessional teams are necessary for success in addressing the complex metabolic dysfunction despite normal weight. 6