Do the Chemicals in our food Impact our Weight?

Are the Chemicals in Your Everyday Products Making You Sick and Obese?

For decades, obesity has been explained with a simple formula: calories in, calories out. But a landmark set of research papers published by Dr. Rob Lustig, alongside 44 co-authors, is challenging that story in a big way. The research points to a category of chemicals called obesogens, compounds hiding in everyday products that appear to directly cause weight gain, not just correlate with it. Lustig, a pediatric endocrinologist at UCSF, discussed the findings with Dr. Casey Means on the Whole New Level podcast, and the implications are worth understanding.

What exactly is an obesogen?

An obesogen is a chemical that specifically drives fat cell accumulation, whether that shows up as subcutaneous fat, visceral belly fat, or fat that quietly builds up in the liver or muscle without ever being visible. These chemicals work by binding to receptors, the proteins that take information from outside a cell and change what happens inside it. Once bound, they can trigger cells to take up extra energy and store it as fat.

The concerning part is where these chemicals show up. Vinyl flooring, flame retardants, electronics, pesticides, disinfectants, thermal receipt paper, and personal care products like lipstick all contain compounds capable of binding to receptors involved in energy metabolism, including the insulin receptor and several others with technical names most people have never heard of. According to Lustig, these obesogens likely account for somewhere between 15 and 20 percent of the obesity problem, a substantial number when nearly three-quarters of American adults are dealing with overweight or obesity.

How they actually cause weight gain

The mechanisms are wide-ranging. Some obesogens directly increase the number of fat cells in the body, an effect that’s especially concerning in babies and young children since fat cell number is largely set by around age two. Others cause epigenetic changes, altering how genes are expressed without changing the DNA itself, and these changes can be passed down through generations. Lustig points to research showing effects persisting across at least four generations, meaning your great-grandmother’s chemical exposure could still be influencing your own metabolism today.

Obesogens also appear to interfere with mitochondrial function, essentially slowing down how efficiently your cells burn energy. Lustig notes that average human body temperature has dropped by about half a degree over the last 25 years, a trend that’s hard to explain through diet alone but fits with widespread mitochondrial disruption from chemical exposure.

Some obesogens aren’t even chemicals you’d expect

One of the more surprising points in the conversation is that some obesogens are compounds many people consider harmless or even actively choose. Artificial sweeteners like sucralose and aspartame, for example, don’t contain calories, but they still trigger an insulin response because the brain “expects” sugar to follow. Since insulin promotes fat storage, these sweeteners can act as obesogens despite having zero calories. Even fructose, a caloric sugar, appears to lay down more fat than its calorie count alone would predict, likely due to its effects on mitochondrial function.

Perhaps most surprising: natural, non-nutritive sweeteners often perceived as “clean,” including stevia and monk fruit, are also listed among the compounds that can raise insulin, according to Lustig.

Pregnancy and early childhood are the most vulnerable windows

Lustig’s research draws on decades of work, including a long-term study tracking pregnant women’s chemical exposure and their children’s subsequent health outcomes. The findings show that chemical levels measured in a pregnant woman’s urine can predict her child’s future obesity and puberty timing. Because fat cells are still actively dividing before around age two, exposure during pregnancy and early infancy carries outsized long-term impact.

Some of the clearest, most actionable takeaways for pregnant women include avoiding smoking (which has well-documented effects on offspring weight) and limiting sugar and artificial sweetener intake, since both appear to cross the placenta and influence fetal fat cell development.

Persistent chemicals that never really left

Many obesogens are so-called “forever chemicals” that remain in the environment long after they’ve been banned or phased out. DDT hasn’t been produced since 1972, yet its breakdown product DDE was still detectable in pregnant women’s urine nearly three decades later, and it continues to predict obesity outcomes in their children. Similarly, PFAS chemicals (once used in Teflon) persist in the environment despite manufacturing changes.

What you can actually do about it

Lustig is clear that avoidance, not detox treatments or supplements, is the most realistic strategy right now. His practical suggestions include:

• Eating organic when possible, since many obesogens are pesticide residues
• Avoiding smoking and secondhand smoke exposure
• Limiting artificial sweeteners, particularly sucralose
• Using PFAS-free cookware and replacing old Teflon pans
• Choosing simpler personal care products, and using resources like the Environmental Working Group’s database to check for safer options
• Prioritizing whole, real food over processed alternatives
• Using an air filter at home, since particulate matter contributes to inflammation and insulin resistance
• Staying well hydrated, which Lustig notes is currently the best-known way to help the body clear these compounds

The bigger picture

Lustig is careful to note that diet and exercise still matter enormously, obesogens aren’t “the whole enchilada.” But the research reframes an important piece of the conversation: some of what’s driving the obesity epidemic isn’t about willpower or food choices at all, but about largely invisible, minimally regulated chemicals embedded throughout daily life. The paper’s authors argue this places responsibility on regulatory agencies like the EPA to catch up, and on individuals to make informed choices in the meantime, since, as Lustig puts it, no one is going to protect you from something you don’t know exists.

This article is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment, and is not a substitute for a conversation with a qualified healthcare provider. Individual health needs vary. If you have questions about your health, we invite you to schedule a consultation with one of our providers.