Almonds Boost Favorable Appetite Hormones Without Affecting Hunger
Obesity affects over 650 million adults worldwide, making the search for foods that help manage appetite crucial. Nuts present scientists with a fascinating contradiction: they’re packed with calories (almonds contain about 579 calories per 100 grams), yet large population studies consistently show that people who regularly eat nuts tend to weigh less.
Specifically, almond consumption links to smaller waist measurements, which matters because belly fat poses serious health risks. Researchers have long wondered exactly how nuts achieve this effect.
A detailed 2023 study published in the European Journal of Nutrition (led by Carter and colleagues) provides new answers by examining what happens inside our bodies after eating almonds compared to a common carbohydrate snack.
How Appetite Hormones Really Work
Our sense of fullness involves complex communication between our gut and brain, directed by key chemical messengers. This important study measured nine critical hormones to understand almonds’ effects. First, C-peptide indicates how much insulin your body produces after eating.
Next, GIP (Glucose-dependent Insulinotropic Polypeptide) triggers insulin release when nutrients enter your system. Glucagon manages blood sugar but also contributes to feeling satisfied. Pancreatic Polypeptide (PP) acts as a powerful natural appetite suppressant.
Other players include GLP-1 and PYY, which slow digestion and boost fullness signals, and ghrelin, often called the “hunger hormone” because its levels rise before meals. Finally, CCK and leptin help signal fullness. Understanding these hormones helps explain why we stop eating.
Testing Almonds vs Carbs: Study Design
This research formed part of a larger registered trial (ANZCTR: ACTRN12618001861246) and involved 140 overweight or obese adults (average age 47.5 years, average BMI 30.7 kg/m², 71% women). Importantly, all participants fasted overnight for at least 10 hours before testing began.
They were then randomly assigned to eat one of two snacks providing identical calories: either 30-50 grams of whole almonds (making up 15% of their daily energy needs) or a carbohydrate-based snack combining a fruit cereal bar with rice crackers.
The nutritional differences were significant: the almond snack offered far more healthy fats (17.2g vs. 5.3g), protein (7.4g vs. 2.5g), and fiber (4.0g vs. 1.2g) per 40-gram serving, while the carb snack contained much more carbohydrate (32.1g vs. 4.6g).
Researchers collected blood samples right before the snack and then at 30, 60, 90, and 120 minutes afterward to measure hormone levels precisely. At these exact same times, participants rated their hunger and fullness using easy-to-understand sliding scales.
Finally, about two hours after the snack, 97 participants (49 almond eaters, 48 carb snack eaters) were offered a large buffet meal where they could eat freely for 30 minutes, allowing scientists to measure actual food intake accurately.
Almonds Slash Insulin, Boost Fullness Hormones
The blood test results revealed dramatic differences in how the body responded to the two snacks. Most strikingly, the total insulin response (measured by C-peptide) was a massive 47% lower in the almond group compared to the carb snack group over the two-hour period.
At every single check point (30, 60, 90, and 120 minutes), C-peptide levels were significantly lower after eating almonds. Meanwhile, key hormones linked to fullness showed strong increases. Glucagon levels were 39% higher overall for almond eaters, while Pancreatic Polypeptide (PP) surged by 45%.
Glucose-dependent Insulinotropic Polypeptide (GIP) also increased by 18% after almonds. Even though the overall total for GLP-1 didn’t differ significantly between groups, almond consumers had notably higher levels at the 60, 90, and 120-minute marks.
However, other hormones like CCK, ghrelin, leptin, and PYY didn’t show significant differences between the groups. These hormone shifts strongly suggested almonds should make people feel fuller.
Why Hunger Didn’t Decrease: The Paradox
Despite these powerful hormonal changes favoring satiety, the participants’ actual experiences told a different story. Ratings for hunger, fullness, satisfaction, and how much more food they thought they could eat showed no difference whatsoever between the almond group and the carb snack group at any time point.
Both groups followed the same pattern: feeling less hungry immediately after their snack, with hunger gradually returning over the next two hours, while feelings of fullness peaked after eating and then slowly declined.
When it came to the buffet meal, the actual food intake also showed no statistically significant difference. Almond eaters consumed an average of 2,887 kilojoules (kJ), while carb snack eaters consumed 3,185 kJ.
Looking closer, almond consumers ate about 270 fewer kilojoules from less-healthy “discretionary” foods like pastries or chips, but this difference didn’t reach statistical significance in this study.
Interestingly, men ate significantly more at the buffet than women, and younger participants ate more discretionary foods than older ones. Essentially, the internal biological signals changed significantly, but people’s conscious feelings of hunger and their actual eating behavior did not.
What This Means for Health and Future Research
So, why didn’t the hormone changes lead to feeling less hungry? Several factors likely play a role. People carrying extra weight sometimes develop resistance to certain fullness hormones, meaning their brains don’t respond as strongly to the signals.
The physical volume of the almond snack (30-50g) was also much smaller than the carb snack needed to match the same calories; a fuller stomach physically stretches and sends strong “stop eating” signals that might have balanced out the hormonal advantage of the almonds.
Furthermore, appetite involves habits, taste preferences, and environmental cues beyond pure biology. Importantly, this doesn’t mean almonds aren’t valuable. Their ability to reduce the insulin spike by 47% is a major metabolic benefit, particularly for blood sugar control and diabetes prevention.
They also deliver superior nutrition – healthy fats, protein, fiber, vitamin E, and magnesium – compared to processed carb snacks. While the immediate hunger reduction wasn’t evident here, regularly choosing almonds over refined carbs supports better overall health.
Future research should test if larger almond portions trigger stronger fullness feelings, whether effects differ in people with healthy weights or diabetes, and how consistent almond consumption influences appetite over weeks or months.
This study reminds us that appetite is incredibly complex, influenced by biology, psychology, and our environment. Choosing almonds remains a smart nutritional upgrade, offering clear metabolic advantages even if the immediate hunger suppression in overweight individuals might be less pronounced than their impressive hormone profile suggests.
Frequently Asked Questions (FAQs) and Concepts
What is Obesity: A medical condition where excess body fat negatively impacts health. It’s important because it increases risks of heart disease, diabetes, and other problems. Body Mass Index (BMI), calculated as weight in kilograms divided by height in meters squared (kg/m²), is used to define it (e.g., BMI ≥ 30 kg/m²). In the study, participants had BMIs between 27.5 and 34.9 kg/m².
What is Satiety: The feeling of fullness and satisfaction after eating that suppresses further hunger. It’s crucial for regulating how much we eat and maintaining a healthy weight. Hormones like GLP-1, PYY, and CCK signal satiety to the brain. In the study, researchers measured if almonds increased satiety more than a carb snack.
What is Hormone: A chemical messenger produced by glands in the body that travels in the blood to control how organs and cells work. They are vital for regulating processes like appetite, growth, and metabolism. Examples measured in the study include insulin, ghrelin (hunger hormone), and GLP-1 (fullness hormone).
What is Insulin: A hormone made by the pancreas that helps cells absorb sugar (glucose) from the blood for energy. It’s essential for controlling blood sugar levels. High insulin levels over time can lead to problems like type 2 diabetes. C-peptide, measured in the study, indicates how much insulin was produced.
What is C-peptide: A substance released into the blood along with insulin when the pancreas produces it. It’s important because it accurately shows how much insulin the body is making. Measuring C-peptide helps assess insulin production. In the study, almond consumption resulted in 47% lower C-peptide levels than the carb snack.
What is GIP (Glucose-dependent Insulinotropic Polypeptide): A hormone released by the gut after eating, especially carbs and fats. It signals the pancreas to release insulin. It plays a role in regulating blood sugar and fat storage. The study found almond eating increased GIP levels by 18% compared to the carb snack.
What is Glucagon: A hormone made by the pancreas that tells the liver to release stored sugar into the blood, raising blood sugar levels when they are low. It also promotes feelings of fullness and helps burn fat. In the study, glucagon levels were 39% higher after eating almonds.
What is Pancreatic Polypeptide (PP): A hormone released by the pancreas mostly in response to eating protein and fat. It strongly signals fullness to the brain and slows down digestion. Its main use is suppressing appetite. PP levels surged 45% higher after almonds in the research.
What is GLP-1 (Glucagon-like Peptide-1): A gut hormone released after eating, especially in response to carbs and fat. It slows stomach emptying, increases fullness feelings, and helps lower blood sugar. Drugs mimicking GLP-1 are used for diabetes and weight loss. Almonds led to higher GLP-1 levels later (60-120 mins) than the carb snack.
What is Randomized Controlled Trial (RCT): A type of scientific study where participants are randomly assigned to different treatment groups (e.g., almond snack or carb snack). This is the gold standard because it minimizes bias and helps prove cause-and-effect. The almond appetite study was an RCT.
What is Area Under the Curve (AUC): A way to measure the total effect or amount of something (like a hormone level) over a specific time period by calculating the area under a line graph of its levels. It gives a single number summarizing the overall response. Researchers used AUC to compare total hormone responses over 120 minutes.
What is Visual Analogue Scale (VAS): A tool to measure subjective feelings like hunger or pain. People mark a point on a straight line (e.g., 10 cm long) between two extremes (e.g., “Not hungry at all” to “Extremely hungry”). It’s simple and widely used in research. The study used VAS to rate hunger, fullness, satisfaction, and desire to eat.
What is Ad libitum intake: Eating where people can consume as much or as little food as they want, without any restriction. It’s important for studying true eating behavior and measuring calorie intake. In the study, participants ate freely from a buffet 2 hours after their snack to see if the snack affected how much they ate later.
What is Postprandial: Referring to the period right after eating a meal (“post” = after, “prandial” = meal). It’s a crucial time for studying how food affects blood sugar, hormones, and metabolism. The researchers measured hormone levels and appetite for 120 minutes postprandially.
What is Energy Density: The number of calories (energy) in a given weight or volume of food (e.g., calories per gram). High-energy-dense foods pack many calories into a small amount (like nuts or butter). Low-energy-dense foods (like vegetables) have few calories per gram. Nuts are energy-dense but didn’t cause weight gain in the study.
What is Glycemic Load: A measure that estimates how much a serving of food will raise a person’s blood sugar level, considering both the type of carbohydrate (glycemic index) and the amount eaten. Low-glycemic-load foods cause smaller blood sugar spikes. Almonds have a low glycemic load.
What is Macronutrient: The three main types of nutrients that provide energy (calories): carbohydrates, proteins, and fats. Understanding their balance in food is key to nutrition. The almond and carb snacks had very different macronutrient profiles (almonds: high fat/protein/fiber, low carb; snack bar: high carb, low fat/protein/fiber).
What is Compensation (in appetite): When the body adjusts for calories eaten at one time by unconsciously eating fewer (or more) calories later. It’s important for understanding how foods affect total daily intake. Researchers wondered if people compensated for almond calories by eating less at the buffet, but no significant difference was found.
What is Statistical Significance (p-value): A measure (p-value) used to tell if a difference observed in a study (e.g., in hormone levels) is likely real and not just due to random chance. A p-value less than 0.05 (p<0.05) is usually considered statistically significant. Many hormone differences in the study had p<0.001, meaning they were highly significant.
What is Standard Error (SE): A measure of how much the average result (mean) from a study sample might vary from the true average of the whole population. It shows the precision of the estimate. Smaller SE means more confidence in the result. Results were reported as Mean ± SE (e.g., C-peptide AUC: AL 153 ± 10, SB 288 ± 10).
What is Body Mass Index (BMI): A simple calculation using a person’s weight and height (formula: weight in kg / height in meters squared). It’s widely used to categorize weight status (Underweight, Normal, Overweight, Obese). Study participants had BMIs between 27.5 (Overweight) and 34.9 kg/m² (Obese Class I).
What is Fasting: Going without food and calorie drinks for a period, usually several hours or overnight. It’s important in metabolic research to get baseline (“starting point”) measurements. Participants fasted for >10 hours overnight before the snack test.
What is Buffet Challenge: A test meal where many different foods are offered freely, and participants can eat as much as they like. It’s used to measure real-world food intake under controlled conditions. A subset of participants ate from a buffet 120 minutes post-snack to measure subsequent energy intake.
What is Core Food: Foods considered essential parts of a healthy diet, providing important nutrients. Examples include fruits, vegetables, lean meats, whole grains, and dairy. In the study buffet, core foods were offered alongside discretionary foods.
What is Discretionary Food: Foods and drinks high in saturated fat, added sugars, salt, or alcohol, not essential for health and often energy-dense but nutrient-poor. Examples include cakes, pastries, chips, sugary drinks. Almond snackers ate slightly fewer discretionary kJ at the buffet (767 vs 1035), but it wasn’t statistically significant.
Reference:
Carter, S., Hill, A.M., Buckley, J.D. et al. Acute feeding with almonds compared to a carbohydrate-based snack improves appetite-regulating hormones with no effect on self-reported appetite sensations: a randomised controlled trial. Eur J Nutr 62, 857–866 (2023). https://doi.org/10.1007/s00394-022-03027-2
