Scientists reveal new explanation for why people are persistently hungry all the time

A study between multiple universities has revisited the link between blood sugar and appetite, and found the relationship is far more complex than previously understood, yielding new insights on how to tame persistent hunger.

The researchers examined blood sugar responses and other indicators from 1,070 participants in the UK and the US, sourcing data from the PREDICT (Personalised REsponses to DIetary Composition Trial) nutrition research project. 

The volunteers ate standardised breakfasts, after which they were free to choose their remaining meals throughout the remainder of the day, observing a fasting window for three hours after breakfast.

They continuously wore blood glucose monitors and recorded what and when they ate each day using a phone app, along with their self-reported hunger levels, over the study period of two weeks. 

The researchers discovered that dips in blood glucose levels, aka “sugar dips,” were significantly linked with appetite levels and energy intake/calorie consumption.

Participants with big blood sugar dips experienced a nine percent increase in appetite, consumed their second meal of the day half an hour sooner, and posted an overall average consumption of 300 calories more throughout the course of the day, than those who didn’t experience these sugar dips.

The research shows “great potential for helping people understand and control their weight and long-term health,” says senior author and genetic epidemiologist Ana Valdes from the University of Nottingham.

“Many people struggle to lose weight and keep it off, and just a few hundred extra calories every day can add up to several pounds of weight gain over a year.”

Prevailing wisdom and research in the modern era focuses heavily on hormones such as ghrelin, but this latest research indicates that glucose levels hours after eating can still have an impact on hunger levels throughout the day, to a far greater extent than previously thought.

“We've now shown that sugar dips are a better predictor of hunger and subsequent calorie intake than the initial blood sugar peak response after eating, changing how we think about the relationship between blood sugar levels and the food we eat,” says nutrition scientist Sarah Berry from King's College London.

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