Why Can’t I Lose Weight: Diet, Health and Weight Loss

Why can’t I lose weight? According to Obesity Reviews, “42% of adults from general populations and 44% of adults from ethnic‐minority populations reported trying to lose weight, and 23% of adults from general populations reported trying to maintain weight annually.”

Obesity contributes to a wide range of medical issues, according to the American Journal of Public Health, which followed more than 200,000 participants over 40 years. The scale of the problem is striking: when the study launched in 1989, about 25% of women were overweight. Today that figure has climbed to at least 66%.

There are countless questions surrounding obesity, and reliable answers can be hard to come by. Here, we dig into research that explains what actually causes obesity and how to fight back effectively.

Let’s take a closer look at what obesity really is and how it affects the body — which ultimately helps explain why weight loss may not be happening for you.

How Big Is the Obesity Epidemic, and What’s Causing It?

What Is Obesity?

The basic definition of obesity is “having too much body fat,” according to MedlinePlus.gov. Obesity differs from being overweight in that overweight is about how much you weigh, while obesity is about how much fat you’re actually carrying. That’s an important distinction — every person who is obese is also overweight, but not every overweight person is obese.

The fight against being overweight has been going on far longer, but obesity is often viewed as the more serious concern. “Excessive or abnormal accumulation of fat or adipose tissue in the body…may impair health” in ways that cause lasting damage, according to Obesity – StatPearls.

Obesity is preventable in many cases, though certain medical conditions do contribute to weight gain and, by extension, to the broader obesity problem.

One major issue is that obesity’s toll on both physical and psychological health is consistently underestimated — not to mention its effect on social interactions and acceptance, according to the Ghana Medical Journal.

With that context, let’s look at what causes obesity and how to work around the barriers standing between you and weight loss.

Obesity Terms and Meanings

A few terms come up often when discussing obesity:

Overweight = Body mass index (BMI) between 25 and 30.

• Obese = BMI of 30 or above
• Obese Class 1 = BMI of 30 to 34.9
• Obese Class 2 = BMI of 35 to 39.9
• Obese Class 3 = BMI of 40+

Causes of Obesity

Researchers point to the “big two” causes of obesity as marketing practices that make calorie-rich foods appealing, and a broad “reduction in physical activity.”

Marketing goes well beyond food commercials and radio spots. The availability and affordability of fast food and convenience foods have both climbed dramatically over the past few decades. There are more quick-eat options today than ever, and nutrition rarely tops the priority list when food is being sold for profit.

As for physical activity, the modern world runs on desk jobs more than ever before. Many people spend eight or more hours a day in front of a screen, at a desk, or in meetings. Even for people who stay active on the job, that activity needs to be separate from dedicated exercise — walking around at work, regardless of step count, doesn’t raise the heart rate enough to meaningfully boost metabolism or drive weight loss.

A quick list of leading contributors to obesity includes:

“Restaurant Dining

Physical Education

Sidewalks and Built Environment

High-Fructose Corn Syrup

Vending Machines” (Critical Reviews in Food Science and Nutrition)

Research from the CDC also addresses the possible causes of obesity, focusing on two main factors: “behavior and genetics.” On the behavior side, contributing factors include:

• Dietary patterns
• Physical activity
• Inactivity
• Medication use

Specific Causes Behind Why You Can’t Lose Weight

Now that the broad causes of obesity are covered, let’s dig into reasons for stalled weight loss you may not have considered before.

Your Brain May Be Working Against You

Your brain genuinely loves the feeling of immediate reward, and food delivers that reward reliably. Instant gratification isn’t always a conscious choice — the brain can effectively nudge you toward eating simply to trigger “good mood” chemicals. (Appetite)

Even after weight loss, this reward-seeking pattern doesn’t necessarily disappear. Research in Brain Sciences found that the brain can continue reacting to food as a source of good feelings even after significant weight has been lost.

You’re Fighting Yourself Over Food

This underlying need for food can make it genuinely difficult to resist the urge to eat. Research points to two common barriers to weight loss: “struggling with self and struggling with implementing the diet.” Without support and guidance, losing weight becomes extremely difficult, according to BMC Women’s Health.

You’ve Recently Quit Smoking

Quitting smoking is excellent for overall health, but it can make weight maintenance genuinely challenging. Many people turn to food for the same gratification once nicotine is out of the picture — a connection strong enough that researchers have studied the mechanism behind it to help counteract the effect, according to Obesity (Silver Spring).

According to Clinical Pharmacology and Therapeutics, “optimizing the health benefits of smoking cessation requires greater understanding of the behavioral and biological relationships between smoking and dietary habits in order to prevent weight gain after quitting smoking.”

Healthy Food Isn’t Always Accessible — Even for Children

Another factor behind obesity is a genuine lack of access to healthy food. According to Public Health Nutrition, food environments in many lower-income areas simply don’t offer healthy options — or those options cost significantly more. The research found “greater exposure to supermarkets and fast food outlets were associated with better diet.”

You Don’t Know Portion Sizes or Food Nutrition

Portion sizing is another underappreciated contributor to obesity. Understanding food nutrition and how it translates into actual serving sizes simply isn’t taught in most schools, or anywhere else for that matter. Fast food and oversized portions make it genuinely hard to learn what a proper amount to eat actually looks like, according to the British Journal of Nutrition.

Bridging the Gap Between Knowing and Doing

Sometimes people already know how to lose weight, how to eat right, and which choices are “correct” — but bridging the gap between knowledge and action is genuinely difficult. Being told to make a change doesn’t automatically make that change easy to stick with, according to the Annual Review of Public Health.

You’re Eating Too Many Processed Foods

On the topic of food availability, processed foods deserve real attention. Whole foods used to be the default, but as life sped up, easy-to-heat, on-the-go processed foods grew popular — to the point of causing genuine health consequences. Eating processed foods is linked to a higher risk of conditions including obesity, according to Current Obesity Reports.

A 2019 study in Cellular Metabolism also examined the impact of ultra-processed foods on weight gain, concluding that “limiting consumption of ultra-processed foods may be an effective strategy for obesity prevention and treatment.”

The National Institutes of Health addressed this too in 2019, finding that people who eat ultra-processed foods consume roughly 500 more calories a day on average than those who choose healthier options. If you’re otherwise eating enough to maintain your weight, an extra 500 calories a day is roughly equivalent to gaining a pound a week.

Your Healthcare Provider Isn’t Offering Adequate Support

One of the toughest barriers to weight loss is inadequate guidance from healthcare providers. Whether the education offered is incomplete or missing entirely, simply telling a patient to “work on their weight” isn’t the same as providing the professional support needed for real success, according to Obesity (Silver Spring).

Your Health and Your Weight

Not every factor behind obesity comes down to food or lifestyle choices. Some medical conditions work against metabolism and other body functions, contributing directly to weight gain. Here’s a look at underlying medical factors tied to weight gain and obesity.

Aging

Age itself is a factor that can’t be ignored. As we get older, metabolism naturally slows and extra weight tends to settle around the midsection. From an obesity standpoint, carrying excess weight can raise leptin levels, potentially leading to leptin resistance — leptin’s job is to suppress energy intake and promote energy expenditure, according to Frontiers in Endocrinology.

Obesity can also accelerate aging-related health issues, compounding the problem further, according to Age.

With the average woman now expected to live beyond 80, building sound dietary habits early is crucial for a long, healthy life, according to the Journal of Midwifery & Women’s Health.

Other health factors worth considering include steroid use, stress, mood, and fatigue — all of which can contribute to being overweight or obese.

How to Combat Barriers to Weight Loss With a Healthy Diet

If any of this sounds familiar, the good news is that some general changes can maximize your natural metabolism and curb hunger without requiring drastic, unsustainable lifestyle overhauls.

Eat More Vegetables

If processed foods make up a large share of your diet, chances are you’re missing out on the nutrient-dense vegetables that help you feel full and support weight loss. Research in the European Journal of Clinical Nutrition shows that eating more vegetables leads to greater weight loss compared to skipping them.

As Scientific Reports puts it simply: “Healthy food choices are happy food choices.”

Lean Toward a Mediterranean Style of Eating

You don’t need to travel to the Mediterranean to see the benefits of this eating pattern. Prioritizing healthy fats, whole foods, and plenty of vegetables — the core of Mediterranean-style eating — primes the body for weight loss and long-term maintenance, along with broader health benefits, according to Nutrition.

Cut Back on Processed Foods

It’s worth repeating: processed foods play an outsized role in obesity. They often carry unnecessary calories in the form of added sugar and fat, along with higher cholesterol and sodium levels than unprocessed alternatives — generally offering little the body actually needs beyond empty calories, according to DMSO: Targets & Therapy.

That same research found that removing common processed items like “margarine, vegetable oils, butter, cream, processed meat, and sugary drinks” from the diet leads to measurable weight loss.

Learn About Portion Sizes

The National Institutes of Health offers helpful guidance here. According to their recommendations, standard serving sizes include:

• Vegetables (2-3 cups)
• Fruits (1.5-2 cups)
• Grains (5-8 ounces)
• Dairy (3 cups)
• Protein foods (5-6.5 ounces)
• Oils (5-7 teaspoons)

These are single-serving measurements, not your total daily target. Dietary needs vary by person, but general daily guidance suggests:

• 5-7 servings of vegetables
• 3-5 servings of grains
• 3 servings of dairy
• 2 servings of meat
• Small amounts of fats
• Sugar-based foods and drinks no more than 1-2 times a week

Drink More Water, Fewer Diet Beverages

No discussion of fighting obesity is complete without addressing water intake. Everyone knows drinking enough water matters, but what about swapping out diet beverages specifically?

Research in the International Journal of Obesity found that replacing diet beverages with water genuinely improves weight-loss outcomes. After 12 months of dieting and maintenance, participants who made the swap saw a greater reduction in BMI than those who continued drinking diet beverages.

Beyond that swap, drinking more water in general supports weight loss on its own. Frontiers in Nutrition reported in 2016 that “increased water intake is associated with loss of body weight.” Water helps reduce overall calorie intake while also supporting hormonal regulation of body fluids.

The effect is significant enough that it holds up even without additional diet or exercise changes. Research in Obesity (Silver Spring) states plainly that “drinking water may promote weight loss in overweight, dieting women.”

The Bottom Line on Why You Can’t Lose Weight

There are many possible reasons behind stalled weight loss. Sometimes it comes down to lifestyle choices, like relying too heavily on processed foods or not drinking enough water. Other times, factors outside your control — underlying health conditions, for example — make weight loss genuinely difficult without extra support.

Getting help doesn’t have to be complicated. Small, sustainable lifestyle changes, paired with realistic goals and a bit of daily consistency, tend to produce the most lasting results. Combine that with increasing water intake and cutting back on processed foods, and meaningful progress becomes far more achievable.

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