Study Shows Peanuts Keep Satisfying Hunger For Longer

22 Jul 2013 --- New research has shown eating peanuts and peanut butter helps manage hunger for longer, even beyond lunch if you eat peanuts at breakfast, and stabilise blood sugar levels for an increased time. The findings of the study "Acute and second-meal effects of peanuts on glycaemic response and appetite in obese women with type 2 diabetes risk: a randomized cross-over clinical trial", published in the British Journal of Nutrition, are good news for everyone and especially people who are overweight and who are at higher risk of diabetes.

The joint American-Brazilian team of investigators (from Purdue University, Indiana, and the Federal University of Vicosa in Brazil) led by principal investigator, Dr. Richard Mattes of Purdue conducted a three phase study using meals containing 42.5g (1.5 ounces) of either peanuts, peanut butter, or no peanuts or peanut butter (the control group). These were consumed by a rigorously selected group of 15 women aged 18-50 who all had BMIs >30 making them clinically obese, as part of a breakfast consisting of orange juice and cream of wheat cereal, followed by a high refined carbohydrate lunch consisting of white bread and strawberry jam.

In the study, blood samples and appetite ratings were taken over a series of three hours following breakfast and again after lunch to assess glucose (blood sugar) control and satiety (feelings of fullness). Peanut butter or peanuts eaten at breakfast were found to promote secretion of the appetite-suppressing hormone peptide YY (PYY). Participants who consumed peanut butter or peanuts reported a lower desire to eat for up to 8 to 12 hours later and maintained lower blood sugar following a high carbohydrate lunch compared to participants that did not include peanut butter or peanuts. Peanut butter had a slightly stronger satiety effect. This is possibly due to the processing of peanut butter which ruptures peanut walls and this may help slow the rate that carbohydrates are absorbed from the gut, resulting in a lower glycaemic response in the blood. That was particularly beneficial for this group of obese women who are at increased risk of type 2 diabetes and who need help with body weight management while maintaining their blood sugar levels.

The investigators suggested that the nutrient benefits of peanuts were synergistic, with their high protein, high fibre, and healthy fats all helping to maintain blood sugar control as well as contribute to feelings of fullness. Peanuts contain more protein by weight per 100g than any other nut and they are good sources of fibre. As Dr Mattes explained: “If you include peanut butter or peanuts at breakfast, you not only diminish the rise in blood sugar at breakfast but also again after lunch, helping to reduce blood sugar over a very large portion of the day.”

Louise McKerchar, European Marketing Director for the American Peanut Council based in London said, “This research is good news for consumers. It means starting the day with breakfast including peanuts sprinkled on whole grain cereal or peanut butter melted into hot toasted breads, is not only delicious but satisfying through the morning and well past lunch time. That helps manage our appetites and control our blood sugar levels so we don’t binge on less healthy snacks. The ‘second meal effect’ observed by these researchers adds to the already impressive case for including peanuts or peanut butter at breakfast time, or indeed anytime, because these ‘hunger busters’ also pack a nutritional punch.”

Peanuts and peanut butter have a strong satiety effect, meaning they help manage appetite and help you feel fuller longer so you don’t want to eat too much too soon. That’s largely due to their very low Glycaemic Index (GI), stemming from to high levels of fibre, protein and healthy fats. GI is a measure of how quickly carbohydrates are turned into sugar in the body and how strongly they stimulate an insulin spike and subsequent crash. Highly refined carbohydrates have high GIs and can cause problems for people trying to lose weight and not binge eat and for people with metabolic syndrome and type 2 diabetes who need to manage blood sugar levels. For both these groups, low GI foods and low Glycaemic Load meals – the impact on blood sugar of an entire meal – are preferable.

Ref: Reis CEG et al. “Acute and second-meal effects of peanuts on glycaemic response and appetite in obese women with high type 2 diabetes risk: a randomised cross-over clinical trial” British Journal of Nutrition 2013: 109, 2015–2023. The research was supported by grants from Brazilian government organisations and the United States Agency for International Development through the Peanut Collaborative Research Support Program. ClinicalTrials.gov registration no. NCT01413126.