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Weight Management Basics: What is Obesity?

By: If you’ve been told you’re obese, you’re not alone, and you’re not defined by a number. More than 42% of American adults live with obesity, according to the CDC. But despite how common it is, obesity remains one of the most misunderstood health conditions. It’s not about willpower. It’s

What is obesity
Picture of Stacy Stern

Stacy Stern

If you’ve been told you’re obese, you’re not alone, and you’re not defined by a number.

More than 42% of American adults live with obesity, according to the CDC. But despite how common it is, obesity remains one of the most misunderstood health conditions.

It’s not about willpower. It’s not about laziness. And it’s not a moral failing.

Obesity is a complex medical condition influenced by genetics, hormones, environment, and metabolism. Understanding what obesity really is and what it isn’t is the first step toward taking control of your health.

Here’s everything you need to know about obesity, how it’s diagnosed, what causes it, and most importantly: how to reverse it.

What Is Obesity?

Obesity is a medical condition characterized by excess body fat that increases the risk of health complications.

It’s not just about how you look. Obesity is diagnosed based on body mass index (BMI), a calculation that uses your height and weight to estimate body fat.

BMI Categories:

  • Underweight: BMI below 18.5
  • Normal weight: BMI 18.5–24.9
  • Overweight: BMI 25–29.9
  • Obesity (Class 1): BMI 30–34.9
  • Obesity (Class 2): BMI 35–39.9
  • Obesity (Class 3): BMI 40 or higher

Important: BMI is a screening tool, not a diagnostic tool. It doesn’t account for muscle mass, bone density, or body composition. A bodybuilder with high muscle mass might have a BMI in the “obese” range, even though they’re healthy.

That’s why a proper obesity diagnosis requires a medical evaluation that considers:

  • Body composition (fat vs. muscle)
  • Waist circumference (abdominal fat is more dangerous than fat in other areas)
  • Medical history (family history, medications, health conditions)
  • Metabolic health (blood pressure, cholesterol, blood sugar)

If your BMI is 30 or higher, or if you have a BMI of 27+ with weight-related health conditions (like diabetes or high blood pressure), you may benefit from medical weight loss treatment.

Weekly Mindset & Weight Loss Tips

Subscribe for expert insights on building confidence, overcoming mental barriers, and achieving lasting weight loss success. Join patients who are transforming both body and mind.Join our newsletter for expert insights on treating melasma, hyperpigmentation, and other skin concerns. Our medical aesthetic team shares practical advice to help you achieve clear, radiant skin.

What Causes Obesity?

Obesity isn’t caused by one thing. It’s the result of multiple factors working together, many of which are outside your control.

1. Genetics

Your genes play a significant role in how your body stores fat, regulates hunger, and burns calories.

Studies show that 40–70% of obesity risk is inherited. If one or both of your parents have obesity, you’re more likely to develop it.

Certain genetic conditions, like Prader-Willi syndrome or hypothalamic obesity, directly cause weight gain.

2. Hormones

Hormones regulate appetite, metabolism, and fat storage. When hormones are out of balance, weight gain becomes nearly inevitable.

Key hormones involved in obesity:

  • Leptin – Signals fullness; leptin resistance causes constant hunger
  • Ghrelin – Triggers hunger; elevated levels increase appetite
  • Insulin – Regulates blood sugar; insulin resistance promotes fat storage
  • Cortisol – Stress hormone; chronic elevation increases belly fat
  • Thyroid hormones – Control metabolism; low levels slow calorie burning

Conditions like hypothyroidism, PCOS, and Cushing’s syndrome can cause weight gain that’s difficult to reverse without medical treatment.

3. Metabolism

Your metabolism determines how many calories you burn at rest. Some people naturally burn more calories than others even when doing nothing.

Factors that slow metabolism:

  • Age (metabolism slows by 2–3% per decade after age 30)
  • Muscle loss (muscle burns more calories than fat)
  • Yo-yo dieting (repeated weight loss and regain)
  • Sleep deprivation (disrupts metabolic hormones)

4. Environment

Your surroundings have a powerful impact on your weight.

Environmental factors:

  • Food availability – Easy access to high-calorie, processed foods
  • Portion sizes – Restaurant meals are 2–3 times larger than they were 30 years ago
  • Sedentary lifestyle – Desk jobs, long commutes, screen time
  • Stress – Chronic stress triggers emotional eating and cortisol spikes
  • Sleep deprivation – Less than 7 hours per night increases obesity risk by 30%

5. Medications

Certain medications cause weight gain as a side effect, including:

  • Antidepressants (SSRIs, tricyclics)
  • Antipsychotics
  • Corticosteroids (prednisone)
  • Beta-blockers (for high blood pressure)
  • Diabetes medications (insulin, sulfonylureas)
  • Antihistamines

If you’ve gained weight after starting a new medication, talk to your doctor about alternatives.

6. Psychological Factors

Emotional eating, binge eating disorder, and depression are strongly linked to obesity.

Food becomes a coping mechanism for stress, sadness, boredom, or trauma. Over time, this pattern leads to weight gain and feelings of shame, which perpetuates the cycle.

Bottom line: Obesity is not a character flaw. It’s a medical condition with biological, environmental, and psychological roots.

How Obesity Affects Your Health

Obesity isn’t just about weight. It increases the risk of serious, life-threatening health conditions.

Immediate Effects

Even before chronic diseases develop, obesity affects your daily life:

  • Reduced mobility – Difficulty walking, climbing stairs, or standing for long periods
  • Joint pain – Extra weight puts stress on knees, hips, and lower back
  • Sleep problems – Obesity increases the risk of sleep apnea (interrupted breathing during sleep)
  • Low energy – Carrying extra weight is physically exhausting
  • Skin issues – Increased risk of rashes, infections, and acanthosis nigricans (dark patches)
  • Mental health struggles – Depression, anxiety, and low self-esteem are common

Long-Term Health Risks

When left untreated, obesity significantly increases the risk of:

Cardiovascular disease:

  • High blood pressure
  • High cholesterol
  • Heart attack
  • Stroke
  • Heart failure

Metabolic disorders:

  • Type 2 diabetes
  • Insulin resistance
  • Metabolic syndrome
  • Non-alcoholic fatty liver disease (NAFLD)

Cancer:

Obesity increases the risk of 13 types of cancer, including:

  • Breast cancer (postmenopausal)
  • Colon cancer
  • Liver cancer
  • Pancreatic cancer
  • Kidney cancer
  • Endometrial cancer

Other conditions:

  • Osteoarthritis (joint degeneration)
  • Gallbladder disease
  • Kidney disease
  • Reproductive problems (infertility, PCOS)
  • Dementia and cognitive decline

The good news: Losing just 5–10% of your body weight can significantly reduce these risks and improve your health.

Myths About Obesity

Let’s clear up some common misconceptions.

Myth #1: Obesity is caused by laziness.

Truth: Obesity is a complex medical condition influenced by genetics, hormones, and environment, not willpower.

Myth #2: All you need to do is eat less and move more.

Truth: For many people, diet and exercise alone aren’t enough. Hormonal imbalances, slow metabolism, and genetic factors require medical intervention.

Myth #3: BMI is the only measure of health.

Truth: BMI is a screening tool, not a diagnosis. Body composition, waist circumference, and metabolic health matter more.

Myth #4: Obesity is permanent.

Truth: Obesity is treatable and reversible with the right medical support, lifestyle changes, and sometimes medication.

Myth #5: Weight loss is linear.

Truth: Weight loss is not a straight line. Plateaus, fluctuations, and setbacks are normal and don’t mean you’re failing.

How to Reverse Obesity

Obesity is both preventable and treatable. With the right approach, you can lose weight, improve your health, and reduce your risk of chronic disease.

1. Medical Weight Loss Programs

Physician-supervised weight loss programs provide:

  • Personalized meal plans tailored to your metabolism
  • Prescription medications (like phentermine, GLP-1s) to control hunger and boost fat loss
  • Weekly check-ins for accountability and progress tracking
  • Metabolic testing to identify hormonal or metabolic barriers
  • Ongoing support to help you maintain your results

At Valley Medical Weight Loss, we’ve helped over 80,000 patients lose weight and keep it off.

2. Nutrition

Focus on:

  • Whole foods – Lean proteins, vegetables, fruits, whole grains
  • Portion control – Use smaller plates, measure servings
  • Balanced macros – Protein, healthy fats, and complex carbs
  • Hydration – Drink at least 64 oz of water per day
  • Meal timing – Eat regular meals to stabilize blood sugar

3. Physical Activity

You don’t need to run marathons. Start with:

  • Walking – 30 minutes per day, 5 days per week
  • Strength training – 2–3 times per week to build muscle
  • Daily movement – Take the stairs, park farther away, stand while working

5. Medical Interventions

For some patients, medication or surgery may be necessary:

  • Prescription weight loss medications (phentermine, GLP-1s, tirzepatide)
  • Hormone replacement therapy (if hormonal imbalances are present)
  • Bariatric surgery (for severe obesity when other methods haven’t worked)

Why Medical Supervision Matters

Losing weight on your own is hard. Medical weight loss programs increase your chances of success by:

  • Identifying underlying causes (hormonal imbalances, metabolic disorders)
  • Providing prescription tools (medications that reduce hunger and boost fat loss)
  • Offering accountability (weekly check-ins keep you on track)
  • Adjusting your plan (as your body changes, so does your treatment)

At Valley Medical Weight Loss, we don’t believe in one-size-fits-all diets. We create personalized plans based on your unique metabolism, health history, and goals.

Take the First Step

If you’re living with obesity, you don’t have to do this alone.

At Valley Medical Weight Loss, we’ve helped over 80,000 patients lose weight and reclaim their health. We offer:

  • Transparent pricing with no hidden fees
  • No-contract plans so you’re never locked in
  • Walk-in convenience at four Phoenix-area locations
  • Physician-supervised care from experienced weight loss specialists

Visit any of our four convenient locations or call today:

Walk-In Hours: Mon–Fri: New patients until 4:30 PM, existing patients until 5:30 PM; Sat: until 2:30 PM; Sun: Closed.

About Valley Medical Weight Loss

For over 15 years, Valley Medical Weight Loss has provided personalized, physician-supervised weight loss and wellness programs. We offer transparent pricing, no-contract plans, and walk-in convenience at four Phoenix-area locations.

More Resources

Weight Loss Programs:

  • Weekly Weight Loss Program
  • Premier Weight Loss Program

Medications & Treatments:

  • GLP-1 Injections
  • Phentermine
  • Hormone Replacement Therapy

Resources:

  • Weight Loss FAQ
  • New Patient Forms

Important Information

General Disclaimer: This article is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment. Always consult your healthcare provider before starting any new weight loss program or medication. Results vary based on individual circumstances.

Weight Management Basics: What is Obesity?

By Dr. Samuel Zuniga, ND
Valley Medical Weight Loss | Chandler, Arizona

If you’ve been told you’re obese, you’re not alone, and you’re not defined by a number.

More than 42% of American adults live with obesity, according to the CDC. But despite how common it is, obesity remains one of the most misunderstood health conditions.

It’s not about willpower. It’s not about laziness. And it’s not a moral failing.

Obesity is a complex medical condition influenced by genetics, hormones, environment, and metabolism. Understanding what obesity really is and what it isn’t is the first step toward taking control of your health.

Here’s everything you need to know about obesity, how it’s diagnosed, what causes it, and most importantly: how to reverse it.

What Is Obesity?

Obesity is a medical condition characterized by excess body fat that increases the risk of health complications.

It’s not just about how you look. Obesity is diagnosed based on body mass index (BMI), a calculation that uses your height and weight to estimate body fat.

BMI Categories:

  • Underweight: BMI below 18.5
  • Normal weight: BMI 18.5–24.9
  • Overweight: BMI 25–29.9
  • Obesity (Class 1): BMI 30–34.9
  • Obesity (Class 2): BMI 35–39.9
  • Obesity (Class 3): BMI 40 or higher

Important: BMI is a screening tool, not a diagnostic tool. It doesn’t account for muscle mass, bone density, or body composition. A bodybuilder with high muscle mass might have a BMI in the “obese” range, even though they’re healthy.

That’s why a proper obesity diagnosis requires a medical evaluation that considers:

  • Body composition (fat vs. muscle)
  • Waist circumference (abdominal fat is more dangerous than fat in other areas)
  • Medical history (family history, medications, health conditions)
  • Metabolic health (blood pressure, cholesterol, blood sugar)

If your BMI is 30 or higher, or if you have a BMI of 27+ with weight-related health conditions (like diabetes or high blood pressure), you may benefit from medical weight loss treatment.

Weekly Mindset & Weight Loss Tips

Subscribe for expert insights on building confidence, overcoming mental barriers, and achieving lasting weight loss success. Join patients who are transforming both body and mind.Join our newsletter for expert insights on treating melasma, hyperpigmentation, and other skin concerns. Our medical aesthetic team shares practical advice to help you achieve clear, radiant skin.

What Causes Obesity?

Obesity isn’t caused by one thing. It’s the result of multiple factors working together, many of which are outside your control.

1. Genetics

Your genes play a significant role in how your body stores fat, regulates hunger, and burns calories.

Studies show that 40–70% of obesity risk is inherited. If one or both of your parents have obesity, you’re more likely to develop it.

Certain genetic conditions, like Prader-Willi syndrome or hypothalamic obesity, directly cause weight gain.

2. Hormones

Hormones regulate appetite, metabolism, and fat storage. When hormones are out of balance, weight gain becomes nearly inevitable.

Key hormones involved in obesity:

  • Leptin – Signals fullness; leptin resistance causes constant hunger
  • Ghrelin – Triggers hunger; elevated levels increase appetite
  • Insulin – Regulates blood sugar; insulin resistance promotes fat storage
  • Cortisol – Stress hormone; chronic elevation increases belly fat
  • Thyroid hormones – Control metabolism; low levels slow calorie burning

Conditions like hypothyroidism, PCOS, and Cushing’s syndrome can cause weight gain that’s difficult to reverse without medical treatment.

3. Metabolism

Your metabolism determines how many calories you burn at rest. Some people naturally burn more calories than others even when doing nothing.

Factors that slow metabolism:

  • Age (metabolism slows by 2–3% per decade after age 30)
  • Muscle loss (muscle burns more calories than fat)
  • Yo-yo dieting (repeated weight loss and regain)
  • Sleep deprivation (disrupts metabolic hormones)

4. Environment

Your surroundings have a powerful impact on your weight.

Environmental factors:

  • Food availability – Easy access to high-calorie, processed foods
  • Portion sizes – Restaurant meals are 2–3 times larger than they were 30 years ago
  • Sedentary lifestyle – Desk jobs, long commutes, screen time
  • Stress – Chronic stress triggers emotional eating and cortisol spikes
  • Sleep deprivation – Less than 7 hours per night increases obesity risk by 30%

5. Medications

Certain medications cause weight gain as a side effect, including:

  • Antidepressants (SSRIs, tricyclics)
  • Antipsychotics
  • Corticosteroids (prednisone)
  • Beta-blockers (for high blood pressure)
  • Diabetes medications (insulin, sulfonylureas)
  • Antihistamines

If you’ve gained weight after starting a new medication, talk to your doctor about alternatives.

6. Psychological Factors

Emotional eating, binge eating disorder, and depression are strongly linked to obesity.

Food becomes a coping mechanism for stress, sadness, boredom, or trauma. Over time, this pattern leads to weight gain and feelings of shame, which perpetuates the cycle.

Bottom line: Obesity is not a character flaw. It’s a medical condition with biological, environmental, and psychological roots.

How Obesity Affects Your Health

Obesity isn’t just about weight. It increases the risk of serious, life-threatening health conditions.

Immediate Effects

Even before chronic diseases develop, obesity affects your daily life:

  • Reduced mobility – Difficulty walking, climbing stairs, or standing for long periods
  • Joint pain – Extra weight puts stress on knees, hips, and lower back
  • Sleep problems – Obesity increases the risk of sleep apnea (interrupted breathing during sleep)
  • Low energy – Carrying extra weight is physically exhausting
  • Skin issues – Increased risk of rashes, infections, and acanthosis nigricans (dark patches)
  • Mental health struggles – Depression, anxiety, and low self-esteem are common

Long-Term Health Risks

When left untreated, obesity significantly increases the risk of:

Cardiovascular disease:

  • High blood pressure
  • High cholesterol
  • Heart attack
  • Stroke
  • Heart failure

Metabolic disorders:

  • Type 2 diabetes
  • Insulin resistance
  • Metabolic syndrome
  • Non-alcoholic fatty liver disease (NAFLD)

Cancer:

Obesity increases the risk of 13 types of cancer, including:

  • Breast cancer (postmenopausal)
  • Colon cancer
  • Liver cancer
  • Pancreatic cancer
  • Kidney cancer
  • Endometrial cancer

Other conditions:

  • Osteoarthritis (joint degeneration)
  • Gallbladder disease
  • Kidney disease
  • Reproductive problems (infertility, PCOS)
  • Dementia and cognitive decline

The good news: Losing just 5–10% of your body weight can significantly reduce these risks and improve your health.

Myths About Obesity

Let’s clear up some common misconceptions.

Myth #1: Obesity is caused by laziness.

Truth: Obesity is a complex medical condition influenced by genetics, hormones, and environment, not willpower.

Myth #2: All you need to do is eat less and move more.

Truth: For many people, diet and exercise alone aren’t enough. Hormonal imbalances, slow metabolism, and genetic factors require medical intervention.

Myth #3: BMI is the only measure of health.

Truth: BMI is a screening tool, not a diagnosis. Body composition, waist circumference, and metabolic health matter more.

Myth #4: Obesity is permanent.

Truth: Obesity is treatable and reversible with the right medical support, lifestyle changes, and sometimes medication.

Myth #5: Weight loss is linear.

Truth: Weight loss is not a straight line. Plateaus, fluctuations, and setbacks are normal and don’t mean you’re failing.

How to Reverse Obesity

Obesity is both preventable and treatable. With the right approach, you can lose weight, improve your health, and reduce your risk of chronic disease.

1. Medical Weight Loss Programs

Physician-supervised weight loss programs provide:

  • Personalized meal plans tailored to your metabolism
  • Prescription medications (like phentermine, GLP-1s) to control hunger and boost fat loss
  • Weekly check-ins for accountability and progress tracking
  • Metabolic testing to identify hormonal or metabolic barriers
  • Ongoing support to help you maintain your results

At Valley Medical Weight Loss, we’ve helped over 80,000 patients lose weight and keep it off.

2. Nutrition

Focus on:

  • Whole foods – Lean proteins, vegetables, fruits, whole grains
  • Portion control – Use smaller plates, measure servings
  • Balanced macros – Protein, healthy fats, and complex carbs
  • Hydration – Drink at least 64 oz of water per day
  • Meal timing – Eat regular meals to stabilize blood sugar

3. Physical Activity

You don’t need to run marathons. Start with:

  • Walking – 30 minutes per day, 5 days per week
  • Strength training – 2–3 times per week to build muscle
  • Daily movement – Take the stairs, park farther away, stand while working

5. Medical Interventions

For some patients, medication or surgery may be necessary:

  • Prescription weight loss medications (phentermine, GLP-1s, tirzepatide)
  • Hormone replacement therapy (if hormonal imbalances are present)
  • Bariatric surgery (for severe obesity when other methods haven’t worked)

Why Medical Supervision Matters

Losing weight on your own is hard. Medical weight loss programs increase your chances of success by:

  • Identifying underlying causes (hormonal imbalances, metabolic disorders)
  • Providing prescription tools (medications that reduce hunger and boost fat loss)
  • Offering accountability (weekly check-ins keep you on track)
  • Adjusting your plan (as your body changes, so does your treatment)

At Valley Medical Weight Loss, we don’t believe in one-size-fits-all diets. We create personalized plans based on your unique metabolism, health history, and goals.

Take the First Step

If you’re living with obesity, you don’t have to do this alone.

At Valley Medical Weight Loss, we’ve helped over 80,000 patients lose weight and reclaim their health. We offer:

  • Transparent pricing with no hidden fees
  • No-contract plans so you’re never locked in
  • Walk-in convenience at four Phoenix-area locations
  • Physician-supervised care from experienced weight loss specialists

Visit any of our four convenient locations or call today:

Walk-In Hours: Mon–Fri: New patients until 4:30 PM, existing patients until 5:30 PM; Sat: until 2:30 PM; Sun: Closed.

About Valley Medical Weight Loss

For over 15 years, Valley Medical Weight Loss has provided personalized, physician-supervised weight loss and wellness programs. We offer transparent pricing, no-contract plans, and walk-in convenience at four Phoenix-area locations.

More Resources

Weight Loss Programs:

  • Weekly Weight Loss Program
  • Premier Weight Loss Program

Medications & Treatments:

  • GLP-1 Injections
  • Phentermine
  • Hormone Replacement Therapy

Resources:

  • Weight Loss FAQ
  • New Patient Forms

Important Information

General Disclaimer: This article is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment. Always consult your healthcare provider before starting any new weight loss program or medication. Results vary based on individual circumstances.

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Wed, Sun: Closed

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