The goal of this clinical trial is to enrich the hamburger meatball with psyllium without impairing its sensory properties and to investigate the effects on acute postprandial lipemia and glycemia, prospective food intake, and some appetite indicators in healthy adults. The main hypotheses of the study are:

1. There is no difference in sensory analysis results between hamburger meatballs enriched with psyllium and those that are not enriched.
2. The rise in postprandial lipids after consuming psyllium-enriched hamburger meatballs is lower than that of classic hamburgers.
3. The rise in postprandial glycemia after consuming psyllium-enriched hamburger meatballs is lower than that of classic hamburgers.
4. The feeling of satiety after consuming psyllium-enriched hamburger meatballs lasts longer, and the feeling of hunger lasts for a shorter period compared to classic hamburgers.
5. Daily food intake after consuming psyllium-enriched hamburger meatballs is less than that of classic hamburgers.

Participants will,

• Eat hamburgers, after fasting for 12 hours, with psyllium-enriched and classic meatballs on intervention days.
• Keep a record of their food intake for the previous and following 24 hours of each intervention.
• Be given fasting and postprandial blood samples.
• Evaluate their hunger and satiety levels on a 100 mm horizontal visual analog scale (VAS) at the beginning and every hour for the following 6 hours of the study.

After preparing 7.5% psyllium-enriched hamburger meatballs (PEHMs) and control hamburger meatballs (CHMs), they will be placed in identical storage containers and frozen at -18°C in a deep freezer. An independent academic will use the Google Random Number Generator to randomly assign two three-digit numbers and code each group accordingly to ensure that the experimental period will be triple-blind.

Participants will be asked to keep a record of their food intake for the previous 24 hours, avoid heavy physical activity, abstain from alcohol before the first day of the study, and to arrive at the study in a state of fasting for 12 hours. On the study day, the participants' sociodemographic information will be collected, anthropometric measurements (height, weight, and fat percentage) will be taken, and fasting blood samples will be collected by a nurse. The participants will then select hamburgers randomly by themselves, with or without (control) 12 g of psyllium, each containing 85 g of hamburger bread, 160 g of 20% fat beef, 2.56 g of salt, and 1.28 g of pepper. They will be asked to consume them with 200 ml of water. The codes for the hamburgers will be written under the plate. The researcher will record which participant consumed which coded hamburger. After waiting two hours in a designated room, postprandial blood samples will be collected in the same order and sent for analysis.

After analyzing the fasting blood values of the participants, if any of them have dyslipidemia (LDL> 149) will be excluded from the study. The remaining participants will be invited back for the second day of the study following a two-week washout period. On this day, the hamburger that they did not consume on the first day will be served to them and the same procedure will repeat.

The guidelines outlined in the CONSORT 2010 statement will be followed during the conduct of the study.

Inclusion Criteria:

• Being willing to participate in the research
• Aged 19 to 35
• No chronic or metabolic disorders
• Body mass index (BMI) between 18.5 and 25 kg/m2

Exclusion Criteria:

• Not being willing to participate in the research,
• Having chronic diseases such as diabetes, hypertension, cancer, metabolic syndrome, chronic kidney disease, dyslipidemia, etc.
• Having a congenital metabolic disease,
• Taking medication to lower blood lipids,
• Being pregnant or breastfeeding,
• Being vegan or vegetarian (as the study requires meat consumption).

All collected IPDs will be shared after publication.

3 mounts after publication

For systematic review and meta-analyses.

Triple blind study design