The authors compared the impact of consuming three commercial dairy products, as morning snacks, on appetite and energy intake at the following lunch. Forty men aged 18 to 50, in good health but overweight (BMI of 25 to 29.9), each took part in four tests separated by at least one week (randomized crossover trial). Each test consisted of consuming a dairy product (semi-skimmed milk, natural yogurt or cheddar) or drinking water (the control product). The portions were isocaloric (200 kcal), yogurt and cheddar were consumed with water to match the volume of milk (410 ml). Subjects had to follow strict instructions for 24 hours before the test, such as limiting alcohol and then eat the standard dinner provided. The morning of the test, a light breakfast was eaten at the study center. Two hours later the subject ate their dairy snack. For lunch they could eat what they liked three and- a-half hours after breakfast.
Questionnaires in the form of Visual Analog Scales were used to measure food intake, physical activity, mood and appetite a set times throughout the morning. Two blood samples were taken (one fasting and 80 minutes after eating the snack) to measure the change in the various markers linked to the feeling of fullness such as the concentration of amino acids, blood sugar, insulin, ghrelin, and peptide tyrosine-tyrosine.
Yogurt snacks led to reduce hunger and delayed subsequent eating
The results suggested that feeling of hunger was significantly weaker (p<0.001) after eating yogurt: by 8% compared to cheese, 10% compared to milk, and 24% compared to water. Energy intake at the next meal (eating whatever they liked) measured in kJ was 11% less after consuming yogurt, 9% less after consuming cheese, and 12% less after consuming milk compared when water was consumed. However, when including the calorie value of the snacks the total energy intake was higher than after drinking water: 4,690 kJ (yogurt) vs 4,301 kJ (water). For biological constants, no post-prandial difference was noted for glucose, insulin, PYY or ghreline. On the other hand, concentrations of alanine and isoleucine were significantly higher after eating yogurt than after eating cheese or drinking milk.