Why are we addicted to ultra-processed foods?

Viewing the Brain, Digestive System, Food Environment, and Eating Behaviour from a Doctor's Perspective

Child and dog eating pasta

"Not hungry... but want to eat chips"

Patients in the clinic sometimes say things like this: "Doctor, I am not hungry. But I always crave something sweet." "Once I open a bag of chips, the whole bag is usually gone." "I can't go without eating chocolate at night."

If we explain this experience with just a single phrase like "due to lack of willpower," we would be leaving out many important biological and behavioral components.

In today's nutrition science, there is growing interest in how Ultra-Processed Foods (UPF), food palatability, eating rate, reward-related learning, and the food environment affect consumption amount and eating behavior.

But first, it is necessary to clearly distinguish a terminology: "Craving UPF" and "having a food addiction disorder" are not the same thing.

What is Ultra-Processed Food?

Ultra-processed foods

The concept of Ultra-Processed Food is related to the NOVA food classification system.

UPFs can contain various industrial ingredients and additives not typically used in home cooking; examples include packaged snacks, sugary drinks, instant noodles, confectionery, and certain ready-to-eat foods. The definition and dietary implications of highly/ultra-processed foods are also discussed in the food-processing literature of the WHO and FAO.

However, being "processed" should not be equated with being "unhealthy." Processing methods such as pasteurization, freezing, fermentation, and canning are important for food safety, preservation, and accessibility.

Therefore— Processed food ≠ automatically unhealthy food

It is important to remember this.

So why are UPFs so appetizing?

There can be more than one reason. At a minimum, the following mechanisms can be considered:

• Food reward and reinforcement

• Palatability

• Energy density

• Eating rate

• Food texture and structure

• Gut–brain signalling

• Learned food cues

• Stress and sleep

• Food environment

  
  

1. Brain Reward System — How does food teach the brain to "want to eat more"?

Brain-reward system

When eating food, the reward-related neural pathways of the brain are activated. While dopamine is an important neurotransmitter here, saying "dopamine is merely a pleasure chemical" would be an oversimplification.

Brain-reward system Dopamine signaling is also related to—

• motivation

• reward learning

• reinforcement

• cue-driven behaviour

  
  

For example— Chocolate → eating → reward

When this experience happens repeatedly, the brain learns to associate cues like the smell of chocolate, its packaging, time, and place with that reward. Later on, just seeing chocolate can lead to a craving.

Therefore, sometimes— It is not "eating because of hunger," but rather "craving because of a cue." This can be the case.

2. Hyper-Palatability — Something more than "good taste"

Friends eating together

The palatability of a food is not just about taste alone. The combination of sweetness + saltiness + fat + flavour + texture + mouthfeel can elevate the sensory appeal of food.

For example—

• crispy chips

• creamy chocolate

• sweetened beverages

• soft baked snacks Various sensory properties are intentionally combined in food products such as these. These kinds of food properties can affect eating behavior and energy intake.

  
  

However, the statement that "manufacturers intentionally make people addicted" should not be written as a universal fact without sufficient evidence. The relationship between food formulation and reward-related eating remains an important area of current research.

3. Eating Rate — "How fast you eat" along with "how much you eat"

Some UPFs are extremely easy to consume. Open it. Eat it. Swallow it. Eat it again. Such easy-to-consume food structures can accelerate the eating rate.

In a 2019 Cell Metabolism randomized inpatient feeding trial, 20 adults were fed a UPF diet and a minimally processed/unprocessed diet for two weeks each. Although the two diets were designed to be matched for presented calories, energy density, macronutrients, sugar, sodium, and fiber, participants consumed an average of 508 kcal more per day during the UPF diet period, which also resulted in weight gain.

This study provides interesting experimental evidence that there may be a causal mechanism between a UPF diet and overeating. However, due to the small sample size and short study duration, a universal conclusion for all UPFs cannot be drawn from this single result alone.

4. What is "Protein Leverage"?

Another hypothesis is the protein leverage hypothesis. According to this theory, the body regulates protein intake more strictly than energy intake, proposing that in a dietary environment with low protein density, total energy intake might increase to meet the protein requirement. There is growing interest in this mechanism because some dietary patterns high in UPFs can have low protein density.

However— Not all UPF cravings and overeating can be explained by protein leverage alone. Palatability, eating rate, energy density, and food environment must also be taken into consideration.

5. Gut–Brain Axis — The stomach and brain are talking to each other

Gut-brain axis

After eating, the intestinal tract sends various signals to the brain.

For example—

• gastric distension

• nutrient sensing

• gut hormones

• vagal signalling

• glucose/metabolic responses

  
  

  These are included.

  
  

Because of this, we cannot simply say, "If the calories are the same, all foods will have the same physiological effect." Food structure, digestion rate, nutrient composition, and eating speed can affect satiety and subsequent intake. In UPF addiction research, the brain-gut-microbiome axis also continues to be studied as an important research area.

6. Stress, Sleep, and Emotional Eating

A person's food choice is not determined by physiological hunger alone. Stress, sleep deprivation, emotional state, and learned habits can also affect eating behavior.

For example— Stress → chocolate Movie → chips Sleepless nights → sugary drink

When such associations happen repeatedly, a learned association can develop between the food cue and eating behavior.

Therefore, if a patient asks, "Why can't I control eating this food?"— It's not just "What do you eat?" but rather "When do you crave it?" This should also be asked.

7. Can it be called "Food Addiction" now?

It is important to be careful with clinical language in this section.

Craving ≠ addiction Frequent UPF consumption ≠ clinical food addiction

The construct of UPF addiction is currently being actively discussed in the research field. A 2024 review evaluated the brain-gut-microbiome mechanisms, addictive-like eating, and withdrawal-related evidence associated with UPF addiction.

A 2025 Nature Medicine commentary also noted a growing scientific debate and public-health discussion on whether highly processed foods might have addictive properties.

However, this field is not yet a settled scientific question. While a 2024 systematic review found associations between UPF consumption and food addiction/eating disorders, the authors pointed out that the included studies were cross-sectional, and lacking longitudinal evidence, causality and directionality could not be definitively established.

Therefore, it is inappropriate to label every patient as a "food addict."

8. UPF and Chronic Disease — What does the evidence say?

Here, it is necessary to differentiate the level of evidence. A 2024 BMJ umbrella review compiled systematic reviews/meta-analyses and evaluated 45 pooled analyses involving nearly 9.8 million participants. Greater UPF exposure had adverse associations with multiple outcomes such as mortality, cardiovascular, metabolic, and mental health.

However, the certainty of most pooled evidence was low or very low, and association is not synonymous with causation.

This point is important. "People who eat UPF have more diseases" is not the same as "UPF alone causes the disease."

Dietary patterns, socioeconomic factors, physical activity, smoking, sleep, healthcare access, and other confounders can affect observational associations.

9. What has the WHO stated?

The WHO's healthy diet guidance emphasizes a dietary pattern based on adequacy, balance, moderation, and diversity, including plenty of fruits, vegetables, pulses, whole grains, and healthy protein sources. It also recommends limiting foods high in free sugars, unhealthy fats, and sodium.

Therefore, in clinical counseling— Rather than an absolute message like "Absolutely no UPF"— A message like "Change to improve the overall dietary pattern" is much more useful.

10. So should UPF be completely cut out?

There is no single answer for everyone. If a patient's UPF consumption—

• increases total calorie intake

• makes weight management difficult

• negatively impacts their diabetes risk profile and dietary quality

• causes binge-like eating/craving ...then it can be clinically reasonable to reduce it.

  
  

However, dietary counseling should not be conducted like a food purity test. Instead— The approach of "What can we add?" can be used.

For example—

• protein-rich foods

• vegetables

• fruits

• legumes

• whole grains

• nuts/seeds Incorporating more of these into the dietary pattern.

  
  

How to advise in practice?

① Find the trigger

Rather than "What are you eating?"— Ask, "When do you start craving it?"

② Change the Food Environment

Instead of constantly fighting cravings with willpower, it is practical to keep trigger foods out of plain sight and make healthier options easily accessible.

③ Base meals on Protein + Fiber

Balanced meals can help with hunger management.

④ Be mindful of Eating Speed

Reevaluate eating very fast or eating while watching a screen.

⑤ Don't forget Sleep and Stress

For some patients, correcting sleep/stress patterns may be a more critical component than adjusting their "diet plan."

Doctor’s Take-Home Message

Craving Ultra-Processed Foods intensely can be due to much more than just "lacking willpower." The taste and texture of the food, ease of consumption, the brain's reward system, habits, stress, sleep, and our daily food environment can all affect cravings.

Therefore— Do not just think, "I need to control myself better."

Instead—

🥗 Eat more nutritious foods

🥚 Include foods with protein and fiber in every meal

🍎 Choose more vegetables, legumes, whole grains, and minimally processed foods

🥤 Reduce sugary drinks and packaged snacks so they don't become your daily default food

🏠 Keep unhealthy snacks at home out of plain sight

😴 Pay attention to your sleep and stress as well

❤️ Do not blame yourself for eating them occasionally

For your health, rather than fearing and completely avoiding one type of food, it is more important to change your overall daily eating pattern for the better.

A healthy diet doesn't need to be perfect. You just need to be able to make good choices most of the time.

Frequently Asked Questions

What is Ultra-Processed Food?

Ultra-Processed Food (UPF) is a category of food products manufactured through multiple stages of industrial processing and formulation, and can include products like packaged snacks, sugary drinks, confectionery, and instant noodles.

Why do people intensely crave Ultra-Processed Foods?

Multiple factors such as palatability, energy density, eating rate, food texture, reward-related learning, gut-brain signalling, stress, sleep, and the food environment can have a combined effect.

Does Ultra-Processed Food cause Addiction?

UPF craving and clinical addiction should not be equated. UPF addiction/addictive-like eating is currently being actively researched, and there are still questions regarding causality and diagnostic boundaries.

Is Dopamine the reason for being addicted to Junk Food?

Dopamine is involved in reward learning, motivation, and reinforcement, but food craving cannot be explained by dopamine alone.

Is UPF consumption associated with Obesity?

Yes. In observational evidence, associations have been found between greater UPF exposure and many adverse health outcomes including obesity. In a randomized inpatient feeding trial, a UPF diet also resulted in higher energy intake and weight gain. However, not all evidence can be directly presented as causality.

Should UPF be completely avoided?

There is no universal rule that everyone must completely cut out UPF. The overall dietary pattern, nutrient quality, portion size, frequency, and individual clinical context should be considered. The WHO also emphasizes a diverse, balanced diet and moderating foods high in unhealthy fats, free sugars, and sodium.

References

1. Hall KD, Ayuketah A, Brychta R, et al. Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake. Cell Metabolism. 2019;30(1):67–77.e3. Randomized inpatient feeding trial; 20 adults. (https://pubmed.ncbi.nlm.nih.gov/31105044/)

   
   

2. Lane MM, Gamage E, Du S, et al. Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses. BMJ. 2024;384:e077310. Umbrella review including 45 pooled analyses and approximately 9.9 million participants. (https://pubmed.ncbi.nlm.nih.gov/38418082/)

   
   

3. LaFata EM, Allison KC, Audrain-McGovern J, Forman EM. Ultra-Processed Food Addiction: A Research Update. Current Obesity Reports. 2024;13:214–223. Review of emerging evidence concerning UPF addiction and addictive-like eating. (https://pubmed.ncbi.nlm.nih.gov/38760652/)

   
   

4. LaFata EM, Moran AJ, Volkow ND, Gearhardt AN, et al. Now is the time to recognize and respond to addiction to ultra-processed foods. Nature Medicine. 2025;31:3586–3587. (https://pubmed.ncbi.nlm.nih.gov/40715815/)

   
   

5. Pereira T, Mocellin MC, Curioni C. Association between ultraprocessed foods consumption, eating disorders, food addiction and body image: a systematic review. BMJ Open. 2024;14:e091223. Important limitation: included studies were cross-sectional; longitudinal evidence was lacking. (https://bmjopen.bmj.com/content/14/12/e091223)

   
   

6. World Health Organization. Healthy Diet. WHO. Guidance on dietary diversity, balance, moderation and healthy food patterns. (https://www.who.int/news-room/fact-sheets/detail/healthy-diet)

   
   

7. Food and Agriculture Organization of the United Nations. Ultra-processed foods, diet quality and human health. FAO. 2019. (https://openknowledge.fao.org/items/192942f3-98b8-4cb0-b612-f9a01d9a10d2)

   
   

8. Mozaffarian D. Regulatory Policy to Address Ultraprocessed Foods. New England Journal of Medicine. 2025;392:2393–2396. Perspective discussing the evidence and policy implications surrounding ultraprocessed foods. (https://pubmed.ncbi.nlm.nih.gov/40544430/)

   
   

9. Ludwig DS. Ultraprocessed Food on an Ultrafast Track. New England Journal of Medicine. 2025;393:1046–1049. Discusses the potential and limitations of the NOVA classification for public-health use. (https://pubmed.ncbi.nlm.nih.gov/40902193/)