In our modern world, convenience reigns! And the quest for quick eats often leaves nutrition on the back burner. It’s no surprise that ultra-processed foods have become a staple in many households. From ready-to-eat meals to packaged snacks, these highly manipulated “foods” offer a tempting shortcut in our fast-paced lives. But alarm bells are ringing, as study after study shows these foods are harmful to metabolic health and add inches to our waistlines.
What a New Study Shows about Ultra-Processed Foods and Leptin Resistance
A recent cross-sectional study looked at the link between eating ultra-processed and leptin levels. To understand what the study found, you must grasp the NOVA classification system, a method used to categorize foods based on their degree of processing.
According to the NOVA system, unprocessed or minimally processed foods, such as fruits, vegetables, and whole grains, should make up the bulk of a healthy diet. Processed foods, like canned vegetables or cheese, undergo some processing. But since their processing is minimal, they retain most of their natural characteristics. Ultra-processed foods, on the other hand, are heavily manipulated and contain additives, preservatives, and artificial ingredients. But what effect do they have on your appetite and metabolic health?
Diet Composition and Leptin Levels: A Concerning Correlation
A study looked at the eating habits of fifty-nine women aged 18 to 40 years old. The participants’ mean calorie intake was 1,624 kcal per day, with a staggering 31.4% of their total energy intake coming from ultra-processed foods. In contrast, unprocessed foods accounted for 52.4%, and processed foods made up 10.4% of their diet.
But just as interesting is the link the researchers discovered between eating ultra-processed foods and the hormone leptin. If you need a refresher on leptin, it’s a hormone your fat cells produce. It plays a key role in regulating appetite and energy balance. After a meal, your leptin level rises, signaling you have sufficient fat stores, and it shuts down your appetite.
As your leptin level rises after a meal, it also stimulates your metabolic rate to help harness the energy you just consumed. Women in the study who consumed more ultra-processed foods had higher levels of leptin, suggesting that ultra-processed foods are linked with leptin resistance.
With leptin resistance, your brain doesn’t detect or respond to even elevated levels of leptin. Your brain doesn’t “hear” the signal that there is enough energy stored as fat. So, you keep eating, past the point where you’ve replenished your energy stores. This impairs your brain’s ability to regulate appetite and energy expenditure appropriately. Another downside of leptin resistance: it can trigger inflammation, obesity, and metabolic disorders.
The study’s findings were consistent across participants with varying body compositions, including those with obesity, normal weight, and constitutional leanness. This suggests that the harmful effects of ultra-processed foods on leptin levels may not be limited to a specific population group.
Why Leptin Resistance Is Problematic for Health and Well-Being
One downside of leptin resistance is it makes it harder to control your food intake. Since your brain doesn’t respond to the appetite-suppressing effects of leptin, you don’t get full as easily. Leptin resistance also is a factor in insulin resistance, where cells don’t respond well to insulin, causing elevated blood sugars. Insulin resistance increases the risk of other health issues, including hypertension, cardiovascular disease, and type 2 diabetes.
Gut Microbiota: The Unseen Accomplice
The study also looked at how ultra-processed foods affect the gut microbiome. We know that what we eat affects the gut microbes that live in our intestinal tract. So, it isn’t surprising that the researchers found different bacteria, based on the diet of the study participants.
While the study did not find a direct correlation between food processing levels and microbiota diversity, the shifts in specific bacterial species raise concerns about the potential impact on metabolic health. The gut microbiome plays a crucial role in digestion, nutrient absorption, and immune function, and imbalances in its composition have been linked to various metabolic disorders.
Reversing Leptin Resistance
As this study shows, ultra-processed foods may contribute to leptin resistance. Other studies show consuming more fiber-rich foods, including fruits and vegetables and lean protein, improves leptin sensitivity, helping to break the cycle of leptin resistance. Quality sleep, aerobic exercise, resistance training, and stress management are also important for balancing leptin levels.
Are there specific foods or nutrients that help balance leptin? Research suggests that consuming foods high in omega-3s, like fish and walnuts helps enhance leptin sensitivity. One study found that omega-3s improve leptin sensitivity, by reducing inflammation.
Whole Foods for Better Health
Ultra-processed food and junk food might call your name when you’re in a hurry, but you’ll serve your health best by eating an unprocessed diet. Not only are ultra-processed foods lower in nutrients, but they contribute to obesity by fueling leptin resistance and insulin resistance, two negatives for your health and waistline. So, skip the drive-through and junk food aisles at the grocery store and focus on, whole, unprocessed fare.
References:
- Women who eat more ultra processed foods more likely to have leptin resistance. Healio.com. Published January 3, 2023. Accessed March 29, 2024. https://www.healio.com/news/endocrinology/20230103/women-who-eat-more-ultraprocessed-foods-more-likely-to-have-leptin-resistance
- Izquierdo AG, Crujeiras AB, Casanueva FF, Carreira MC. Leptin, Obesity, and Leptin Resistance: Where Are We 25 Years Later? Nutrients. 2019 Nov 8;11(11):2704. doi: 10.3390/nu11112704. PMID: 31717265; PMCID: PMC6893721.
- Yao H, Fan C, Fan X, Lu Y, Wang Y, Wang R, Tang T, Qi K. Effects of gut microbiota on leptin expression and body weight are lessened by high-fat diet in mice. Br J Nutr. 2020 Aug 28;124(4):396-406. doi: 10.1017/S0007114520001117. Epub 2020 Mar 26. PMID: 32213218.
- Yan Y, Jiang W, Spinetti T, Tardivel A, Castillo R, Bourquin C, Guarda G, Tian Z, Tschopp J, Zhou R. Omega-3 fatty acids prevent inflammation and metabolic disorder through inhibition of NLRP3 inflammasome activation. Immunity. 2013 Jun 27;38(6):1154-63. doi: 10.1016/j.immuni.2013.05.015. PMID: 23809162.
- Chacińska M, Zabielski P, Książek M, Szałaj P, Jarząbek K, Kojta I, Chabowski A, Błachnio-Zabielska AU. The Impact of OMEGA-3 Fatty Acids Supplementation on Insulin Resistance and Content of Adipocytokines and Biologically Active Lipids in Adipose Tissue of High-Fat Diet Fed Rats. Nutrients. 2019 Apr 12;11(4):835. doi: 10.3390/nu11040835. PMID: 31013835; PMCID: PMC6520951.
- Izquierdo AG, Crujeiras AB, Casanueva FF, Carreira MC. Leptin, Obesity, and Leptin Resistance: Where Are We 25 Years Later? Nutrients. 2019 Nov 8;11(11):2704. doi: 10.3390/nu11112704. PMID: 31717265; PMCID: PMC6893721.
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