Browse evidence-based analysis of health-related claims and assertions
Scientists found that a fat chemical (15-HETE) physically sticks to a key energy sensor (AMPK) in fat cells, turning it on and helping the cells burn more energy to make heat.
Mechanistic
When scientists grew fat cells with this specific bacteria (Sphingomonas), the cells stopped making a key fat-burning chemical and heat-producing proteins—but when they used a different common bacteria (E. coli), nothing changed.
When scientists gave a specific fat chemical (15-HETE) to mice whose heat production was blocked, it brought back their ability to burn fat and generate heat, even if the bacteria or enzyme blocking it were still present.
People who are overweight or obese tend to have less of a specific fat-related chemical (15-HETE) in their blood than lean people, and the more weight they have, the less of this chemical they have.
Correlational
In mice, a type of gut bacteria called Sphingomonas paucimobilis moves to belly fat during inflammation and blocks the body’s ability to burn calories for heat by interfering with a key fat-burning chemical and its signaling pathway.
When young men slept less, their bodies released more of the stress-related chemical norepinephrine, especially at night and in the morning, which may be a sign their stress system was overactive.
Causal
When young men slept less, they burned a little more energy during the night because they were awake longer—but this extra burn didn’t add up to more total energy burned over the whole day.
Even after sleeping only 3.5 hours a night for three nights, young men burned the same total amount of energy and used the same mix of carbs and fats as when they slept 7 hours.
When young men slept less, their body’s internal temperature dropped slightly over two days, suggesting their body’s natural daily temperature cycle was disturbed.
As you heat any oil, the number of smelly, toxic aldehyde chemicals goes up steadily — and soybean oil spikes the most right at frying temperatures.
Descriptive
After sleeping only 3.5 hours a night for three nights, young men reported feeling much hungrier and more tempted to eat, and less full after meals, even when they ate the same food as when they slept longer.
When young men slept only 3.5 hours a night for three nights, their bodies produced less of the hormones that tell them they’re full, making them feel hungrier.
Glyoxal, a toxic chemical formed when oil is heated, is most common in oils like lard and palm oil because they contain myristic acid and oleic acid.
When you heat oil, the good unsaturated fats break down and disappear, leaving behind more of the saturated fats — so the oil becomes more saturated over time.
You can tell what kind of oil was heated by the chemicals it makes — hexanal means it had linoleic acid, while octanal and nonanal mean it had oleic acid.
Olive oil, which has lots of oleic acid, makes more of certain toxic aldehydes like 4-HNE and 2-decenal when heated than oils like soybean or palm.
The more linolenic acid (a type of omega-3) an oil has, the more MDA and 4-HHE it makes when heated — these chemicals only show up in oils with this specific fat.
Oils with lots of unsaturated fats, like soybean oil, produce way more toxic chemicals when heated to frying temperatures than oils with more saturated fats.
When you cook oils at high heat, especially above 180°C, they break down and make more harmful chemicals — the hotter it gets, the more chemicals form.
To be safe, don’t heat hemp oil hotter than 190°C or for longer than an hour — this is the advice from the researchers.
Hemp oil already had tiny amounts of certain unhealthy trans fats, but heating it didn’t make any more of them.
Hemp oil is mostly made up of linoleic acid, with smaller amounts of two other healthy fats, and heating doesn’t change which fats are most common.
Hemp oil with garlic or chili added stays fresher longer when heated than plain hemp oil.
Even when you heat hemp seed oil really hot for a long time, it doesn't go bad in a way that makes it unsafe by standard food quality rules.