Home
Why Do We Become Overweight?
Why is it that more people are becoming overweight, even with widespread access to fitness programs, healthy living guidelines, and the rising popularity of sugar-free diets or gluten-free choices? Despite the blame often placed on fats, sugars, or fast food, the reality is much more complex. To understand why, we need to look at multiple factors, including technical causes, lifestyle shifts, social dynamics, and even evolutionary biology.
The Technical Causes Behind Weight Gain
1. An Increase in Calorie Consumption
The mid-20th century marked a turning point. Advancements in food production made food far cheaper and more accessible than it had been before. Sugar and vegetable oils (such as corn, sunflower, and soy oils) became staples. These ingredients, added to a myriad of processed products, made food tastier, more appealing, and significantly more calorie-dense. This change laid the groundwork for modern-day overeating.
Take the United States, for example. Studies comparing calorie consumption in 1970 and 2000 show startling increases. Children consumed 300 additional calories daily, while adults consumed 500 more [3]. A 20% rise in caloric intake over three decades is no small feat. With every extra bite, we inch closer to chronic weight gain.
2. Decreased Energy Expenditure
While calorie consumption has risen, energy expenditure has decreased. This is largely due to changes in NEAT—Non-Exercise Activity Thermogenesis. NEAT captures all the small, everyday activities that burn calories, from walking to talk on the phone to taking the stairs.
The mid-20th century marked a turning point. Advancements in food production made food far cheaper and more accessible than it had been before. Sugar and vegetable oils (such as corn, sunflower, and soy oils) became staples. These ingredients, added to a myriad of processed products, made food tastier, more appealing, and significantly more calorie-dense. This change laid the groundwork for modern-day overeating.
Take the United States, for example. Studies comparing calorie consumption in 1970 and 2000 show startling increases. Children consumed 300 additional calories daily, while adults consumed 500 more [3]. A 20% rise in caloric intake over three decades is no small feat. With every extra bite, we inch closer to chronic weight gain.
2. Decreased Energy Expenditure
While calorie consumption has risen, energy expenditure has decreased. This is largely due to changes in NEAT—Non-Exercise Activity Thermogenesis. NEAT captures all the small, everyday activities that burn calories, from walking to talk on the phone to taking the stairs.
1. The Transition to Adulthood
Remember those busy college years? You may have grabbed quick meals on the go, stayed out late, walked across campus, and even juggled part-time jobs. Such an active lifestyle often kept weight in check. However, as life stabilizes, caloric intake doesn’t always adjust to reduced activity levels. Starting a family, working a sedentary office job, or achieving a bigger paycheck (leading to dining out more frequently) are all factors that contribute to gradual weight gain.
Many blame a "slow metabolism" as they age, but studies reveal this isn’t the primary issue. Instead, the shift in lifestyle is to blame [7]. Less physical activity and greater caloric intake create the perfect storm for creeping weight gain.
Remember those busy college years? You may have grabbed quick meals on the go, stayed out late, walked across campus, and even juggled part-time jobs. Such an active lifestyle often kept weight in check. However, as life stabilizes, caloric intake doesn’t always adjust to reduced activity levels. Starting a family, working a sedentary office job, or achieving a bigger paycheck (leading to dining out more frequently) are all factors that contribute to gradual weight gain.
Many blame a "slow metabolism" as they age, but studies reveal this isn’t the primary issue. Instead, the shift in lifestyle is to blame [7]. Less physical activity and greater caloric intake create the perfect storm for creeping weight gain.
Here’s the challenge. Automation and convenience have replaced physical activity in daily life. Grocery shopping is an occasional event, often ending with a delivery. Driving or using electric scooters has replaced walking or biking. Simple chores, such as handwashing laundry or taking out the garbage, are now streamlined to require minimal effort. Studies in the U.S. alone have shown that people burn approximately 100 fewer calories per day compared to 50 years ago [5].
What’s truly fascinating is how individual NEAT levels vary. Differences in everyday movement can range up to a stunning 2000 calories per day [6]. A factory worker on their feet all day will burn considerably more calories than someone working remotely from the comfort of their couch. The choice is clear—less movement creates more opportunities for surplus calories to be stored as fat.
What’s truly fascinating is how individual NEAT levels vary. Differences in everyday movement can range up to a stunning 2000 calories per day [6]. A factory worker on their feet all day will burn considerably more calories than someone working remotely from the comfort of their couch. The choice is clear—less movement creates more opportunities for surplus calories to be stored as fat.
How Lifestyle Shapes Our Weight
The Evolutionary Drive to Overeat
The Social and Psychological Impact of Obesity
Tackling the Complexity Together
2. The Weekend and Holiday Trap
How often do we eat mindfully during the week only to indulge heavily during the weekend? Birthday parties, holidays like Thanksgiving, or even casual get-togethers can lead to unchecked calorie surpluses. These indulgences often seem minor in isolation but, over time, their cumulative effect can be significant. Gaining even 0.5–1 kg annually may not seem alarming, but in 10–15 years, this slow gain leads to noticeable lifestyle changes, like struggling to button your shirts [9].
3. Significance of Visibility and Accessibility
Food delivery services, widespread restaurant options, and even calorie-dense snacks available in convenience stores make overeating incredibly easy. Food is no longer something we actively seek—it’s always within arm’s reach.
How often do we eat mindfully during the week only to indulge heavily during the weekend? Birthday parties, holidays like Thanksgiving, or even casual get-togethers can lead to unchecked calorie surpluses. These indulgences often seem minor in isolation but, over time, their cumulative effect can be significant. Gaining even 0.5–1 kg annually may not seem alarming, but in 10–15 years, this slow gain leads to noticeable lifestyle changes, like struggling to button your shirts [9].
3. Significance of Visibility and Accessibility
Food delivery services, widespread restaurant options, and even calorie-dense snacks available in convenience stores make overeating incredibly easy. Food is no longer something we actively seek—it’s always within arm’s reach.
1. Our Biology Loves Delicious Food
Humans evolved to thrive in environments with scarce food. Our bodies are hardwired to seek out calorie-dense options. When food triggers dopamine releases—whether it’s sweet, salty, or fatty—it becomes harder to stop consuming it. Thriving on fast food or indulgent desserts isn’t a reflection of weakness but rather an evolutionary response to what our bodies perceive as concentrated energy sources [13].
Anthony Sclafani’s 1976 study with rats provides useful insight. When given access to highly palatable foods, the animals overeaten, rapidly gained weight, and showcased behaviors eerily similar to humans around snacks like chocolate or chips. Similar experiments with humans revealed a 70% surplus in caloric intake when participants had nonstop access to snack options [11].
2. Processed Foods Versus Whole Foods
A 2019 study by Kevin Hall examined differences between fast food (FF) and healthier, minimally processed diets (HD). Predictably, participants on FF diets consumed an excess of 500 calories per day and gained 0.5 kg in just two weeks. Conversely, those on HD diets naturally ate to satiety and lost 0.3 kg in the same timeframe. The conclusion? Processed foods, being tastier and denser in calories, are far easier to overeat compared to whole foods [15].
Humans evolved to thrive in environments with scarce food. Our bodies are hardwired to seek out calorie-dense options. When food triggers dopamine releases—whether it’s sweet, salty, or fatty—it becomes harder to stop consuming it. Thriving on fast food or indulgent desserts isn’t a reflection of weakness but rather an evolutionary response to what our bodies perceive as concentrated energy sources [13].
Anthony Sclafani’s 1976 study with rats provides useful insight. When given access to highly palatable foods, the animals overeaten, rapidly gained weight, and showcased behaviors eerily similar to humans around snacks like chocolate or chips. Similar experiments with humans revealed a 70% surplus in caloric intake when participants had nonstop access to snack options [11].
2. Processed Foods Versus Whole Foods
A 2019 study by Kevin Hall examined differences between fast food (FF) and healthier, minimally processed diets (HD). Predictably, participants on FF diets consumed an excess of 500 calories per day and gained 0.5 kg in just two weeks. Conversely, those on HD diets naturally ate to satiety and lost 0.3 kg in the same timeframe. The conclusion? Processed foods, being tastier and denser in calories, are far easier to overeat compared to whole foods [15].
On a societal level, cultural norms and expectations also perpetuate the obesity epidemic. Food marketing targets affordability, convenience, and indulgence rather than nutrition. Larger portion sizes at restaurants and an endless variety of calorie-packed foods only fuel overeating behaviors. And while education on healthy choices is readily available, it often feels overshadowed by larger systemic challenges—like income inequality or lack of access to fresh, whole ingredients.
3. Cheap Calories Equal Greater Consumption
Not only is processed food tastier, but it’s also far more affordable. Refined carbs, cheap oils, and sugar cost a fraction of high-quality protein or fiber-rich produce, making them staples for many. Because of this, lower-income households often face higher BMI levels, with ultra-processed options serving as the backbone of their caloric intake. The affordability of these foods, while seemingly helpful for budgets, comes at a cost to long-term health [16].
Not only is processed food tastier, but it’s also far more affordable. Refined carbs, cheap oils, and sugar cost a fraction of high-quality protein or fiber-rich produce, making them staples for many. Because of this, lower-income households often face higher BMI levels, with ultra-processed options serving as the backbone of their caloric intake. The affordability of these foods, while seemingly helpful for budgets, comes at a cost to long-term health [16].
Ultimately, the reality of obesity is summed up in one truth—there are no easy answers. Genetics, lifestyle, and personal habits all play their part. However, acknowledging the challenges is a significant first step. Empowering yourself with knowledge about NEAT, making conscious efforts to prioritize whole, minimally processed food, and creating long-term habits can reshape outcomes.
To those navigating this personal transformation—remember, you’re not alone. Understanding the factors at play can bolster your confidence and decisions. Becoming healthier isn’t about guilt or deprivation. It’s about finding balance, taking small steps, and redefining what wellness looks like in your life.
To those navigating this personal transformation—remember, you’re not alone. Understanding the factors at play can bolster your confidence and decisions. Becoming healthier isn’t about guilt or deprivation. It’s about finding balance, taking small steps, and redefining what wellness looks like in your life.
Sources
- Global Obesity Levels
- Obesity and overweight (World Health Organization)
- Increased food energy supply is more than sufficient to explain the US epidemic of obesity (Swinburn, 2009)
- Non-exercise activity thermogenesis (NEAT) (Levine, 2002)
- Trends over 5 Decades in U.S. Occupation-Related Physical Activity and Their Associations with Obesity (Church, 2011)
- Human energy expenditure in affluent societies (Black, 1996)
- Daily energy expenditure through the human life course (Pontzer, 2021)
- A Prospective Study of Holiday Weight Gain (Yanovsky, 2015)
- Long-term increase of fat mass after a four-week intervention with fast-food-based hyper-alimentation (Ernersson, 2010)
- Weight Gain over the Holidays in Three Countries (Helander, 2016)
- Spontaneous overfeeding with a 'cafeteria diet' in men (Larson, 1995)
- Ad libitum food intake on a "cafeteria diet" in Native American women (Larson, 1995)
- How palatable food disrupts appetite regulation (Erlanson-Albertsson, 2005)
- Stephan Guyenet - The Hungry Brain (2018)
- Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain (Hall, 2019)
- Common Variant in the FTO Gene and its link to BMI (Frayling, 2009)
Contact us by e-mail: info@fizikl.co
License Number: 32779
License Address: Dubai Silicon Oasis, Techno Hub 2, I132-H, Dubai, the United Arab Emirates
FIZIKL IQ – FZCO