Is Obesity a Choice?

Posted on by Jonas Koblin

What really causes obesity? Is it just a lack of willpower, or do genetics and the environment play a larger role? Calorie-dense foods, hormonal changes, genetic predispositions, and cultural habits all contribute to weight gain – or loss. Scientific research highlights the roles of metabolism, portion sizes, accessibility, and even gut bacteria in shaping behaviors and body weight. 

the full story
01 Obesity

When we see someone overweight, there are three reasons most people point to: 

  • Lack of self-control
  • Genetics
  • or the Environment

But which one is it really?

Will power myth
02 Obesity

It’s clear: obesity is a matter of willpower and simple energy balance: calories in minus calories out. If you eat more than you burn, you’ll gain weight. The average adult needs 1,700 to 2,500 calories per day. If you exceed that, your body stores the excess as fat and muscle. It is, therefore, the kind of food you eat that makes all the difference.

Eating calorie-dense foods with little nutritional value can easily push you into a calorie surplus, as they are high in energy but leave you feeling hungry. Eating plenty of vegetables, wholegrains, and nuts makes staying in shape much easier.

03 Obesity

The logical conclusion is that if someone is overweight, they must lack the willpower to control their diet. And there are countless success stories of people who changed their eating habits, started exercising, and transformed their bodies. This proves that obesity is not inevitable. It’s a deliberate choice, guided by thoughtful decision-making, self-discipline, and the development of healthier habits. But is it a choice that everyone can make? After all, you are what you eat. Right? Wrong! 

Genetics influence
04 Obesity

Genetics play a massive role. You don’t choose your body. Instead your body may choose for you. Consider this: genetics influence how fast your metabolism runs, how hungry you feel, and how your body stores fat.  The same food can make some people feel fired up because their body uses that energy right away, while others likely feel tired, as their body stores the calories in the form of fat instead of using it. And then there are also rare monogenic cases.

It is estimated that 2 to 5% of obese people are this way because of a single genetic mutation. For example, the Prader-Willi syndrome results from a gene inactivation on chromosome 15, leading to an insatiable hunger that begins around age 2. Children born with Alström syndrome, will be colorblind and overweight—regardless of willpower or lack of self-control. And if your body doesn’t produce enough of the hormone leptin, you could overeat simply because you never feel satisfied, no matter how much you consume.

09 Obesity

Genetics also influence how your body stores fat and whether your metabolism burns calories efficiently. This means that even if two people eat the exact same diet, one may gain weight while the other remains slim. When biology is against you, and your body is wired to retain energy, can you really be blamed for gaining weight? Maybe!

Environmental & cultural influences
10 Obesity

It’s neither willpower nor genetics, but your surroundings that shape who you are. After all, you eat what’s available, often regardless of how full you feel. Research has shown that accessibility plays a massive role in our eating habits.

One study on cafeterias showed that if fatty foods are moved just a little further from the aisle, consumption drops between 8 to 16 percent. Another study on college students demonstrated that changing the visibility and distance of unhealthy snacks can decrease consumption sixfold.

11 Obesity

Portion sizes, which vary widely between cultures, can trick your brain into consuming more than you need. One controlled experiment concluded that increasing portion sizes by 50% for 11 days led to people eating more, regardless of their appetite, and continuing this habit even after the experiment ended. 

What’s considered a large soda in one country might look small in another. Over time, these environmental nudges can lead to significant changes in body weight, which may help explain why Japan has one of the lowest obesity rates in the world, while 1 in 5 children in the US are overweight.

12 Obesity

And if you study immigrants who move to a new culture, you will see that they adopt the diet of their new home. Research shows that second-generation Asian Americans are larger than first-generation immigrants, who stick more closely to traditions from their home countries, and eat more fresh and less processed food.

The fact that people from countries with lower obesity rates gain weight when moving to countries like the US, Egypt, or Australia, suggests that culture plays the major role in shaping your body. As the saying goes, you are the average of the 5 people you spend the most time with.

13 Obesity

But if the environment dictates the foods you can access, their quantity, and their quality, is obesity in certain cultures inevitable? In other words: If you live in a world where there are only apples, you will probably eat apples. By extension, obesity must largely be a product of the environment you live in. Right? – Well, it’s complicated.

microbiome matters
14 Obesity

Your behaviors around food are often the result of complex interactions between your personality, your DNA, and your environment. For example, your gut microbiome is directly influenced by what you eat and where you live, it then controls how you behave around food, and how your body reacts to certain nutrients.

If you eat asparagus it will support the growth of Christensenella Minuta, a bacterium that was shown to promote weight loss, and decrease inflammation. A diet rich in fats can increase the presence of Firmicutes, which maximize the extraction of energy, make you crave more, and can contribute to overeating.

15 Obesity

So the answer may seem simple: If you change your diet, you change your bacteria, and eventually it becomes simpler, right? Well yes, but actually no. A study published in Nature, a scientific journal, in 2023 showed that bacteria populations inside our body are associated with certain neighborhoods, due to things like pollution, sanitation, or access to good food. This means that even a change in diet may not be enough to counteract genetic or environmental influences.

Does this mean that it’s useless to even try? No! You can train your brain by developing new habits—even if they seem small, such as starting the day with one apple slice. You can learn about your genetic predispositions and take steps to consciously avoid certain situations. And you can change your immediate environment. Simple rearrangements will reduce your ability to snack.

what do you think?
16 Obesity

What do you think? Did you know how complex this topic actually is? What about your relationship with food and your own body? Share your thoughts and experiences in the comments below!

Sources

Dig deeper!

Classroom activity

Objective:

Students will explore the causes of obesity by analyzing willpower, genetics, and environmental factors, assessing how these interact to shape individual and societal health.

Materials Needed:

  • Sprouts video on Obesity.
  • Case studies or statistics on obesity (see Dig Deeper).
  • Chart paper or whiteboards for group activities.
  • Markers, sticky notes, or pens for brainstorming.

Duration:

60 minutes

Steps:

  1. Introduction and Context (10 minutes):
    • Begin by asking: “What do you think is the primary cause of obesity: personal willpower, genetics, or the environment?”
    • Write responses on the board, categorizing them into the three areas (Willpower, Genetics, Environment).
    • Read or summarize Scenes 1–3 aloud, presenting the three main perspectives.
    • Emphasize the complexity of the topic and the interplay of factors.
  2. Group Exploration of Causes (20 minutes):
    • Divide into Groups:
      • Assign each group one of the three causes: Willpower, Genetics, or Environment.
      • Show Sprouts Video on Obesity. 
    • Group Tasks:
      • Groups review relevant scenes from the Video:
        • Willpower: Scenes 4–12
        • Genetics: Scenes 14–24
        • Environment: Scenes 26–42
        • Discuss and answer these prompts:
          • What evidence supports this cause as a major factor in obesity?
          • What examples from the script or real life illustrate this cause?
          • Are there limits to this explanation? How do other factors interact with it?
        • Record key points on chart paper or a shared whiteboard.
        • Presentations and Discussion (15 minutes):
          • Each group shares their findings, focusing on:
            • Key evidence for their assigned cause.
            • How their cause connects to others (e.g., environment influencing willpower).
          • Allow time for questions from classmates after each presentation.
          • Highlight overlapping ideas or points of disagreement.
          • Ask: “Which cause do you think has the biggest impact? Why?”
        • Reflection and Solutions Workshop (10 minutes):
          • Ask students to write short responses to these prompts:
            • Which cause do you think plays the biggest role in obesity?
            • What strategies could address obesity by targeting this cause?
          • As a class, brainstorm actionable steps that individuals, communities, and governments could take to reduce obesity.
          • Write ideas on sticky notes and organize them under categories: Personal, Environmental, Policy Changes.
        • Conclusion and Sharing (5 minutes):
          • Summarize Key Insights:
            • Reiterate that obesity is a complex issue influenced by the interplay of willpower, genetics, and environment.
          • Share Reflections:
            • Allow a few students to share their reflections or proposed solutions.
          • Closing Question:
            • End with a thought-provoking question: “How might understanding these factors change how we address obesity in society?”

Assessment:

  • Evaluate group engagement and the depth of analysis during discussions.
  • Assess the connections made between the script content and real-world examples.
  • Encourage thoughtful and evidence-based participation throughout the exercise.

This exercise encourages critical thinking and collaboration, providing a comprehensive understanding of obesity’s causes and solutions.

Collaborators

  • Script: Jonas Koblin and Ludovico Saint Amour di Chanaz, PhD
  • Cartoon artist: Pascal Gaggelli
  • Producer: Selina Bador
  • Voice artist: Matt Abbott
  • Coloring: Nalin
  • Editing: Peera Lertsukittipongsa
  • Sound Design: Miguel Ojeda
  • Publishing: Vijyada Songrienchai