Satiety and hunger levels have been associated with energy imbalances. Overeating is one of the main causes of obesity. As well as obesity there are other serious health risks and diseases such as; type 2 diabetes, high blood pressure, high cholesterol, cancers, coronary heart disease and strokes (Mokdad, Ford, Bowman, Dietz, Vinicor, Bales, & Marks, 2003). To counteract this, reducing weight or maintaining weight is associated with the consumption of fruit and vegetables within the diet. Studies have predominantly indicated that incorporating healthy foods such as fruit and vegetables into the diet, can promote satiety and decrease energy intake (Rolls, Ello-Martin, & Tohill, 2004). This study aims to determine whether whole oranges or orange juice has the most differential effect on satiety and hunger levels, while participants are in a fasted state.

Aims

To examine the different fruit types and the effect it may have on satiation levels for fasted participants.

Objectives

Implement a two-armed cross over study to determine the differences between fruit types.
To examine the relationship between appetite levels and different fruit types.
To understand how appetite levels, change over time when in a fasted state.

Hypothesis

Consuming the whole orange instead of the orange juice will decrease satiety and hunger levels when in a fasted state.

Procedure

Before starting the experiment, ensure participants have had a 12 hour fast where no food or drink, (other than water), has been consumed within that time. Record the participants; age, weight, sex and height. Next, weigh out either 226g of unpeeled orange segments or 431ml of pure orange juice, (both 125 calories). Accompanied by 150ml of semi-skimmed milk, as well as 50g of cornflakes. Place all items onto the tray. Ask the participant to enter the eating booth, so no other variables can affect the answer given. Using the visual analogue scale, the subject must indicate their appetite according to the scale, this must be done before breakfast. Pass the tray through to the participant and ask them to consume all of the breakfast provided.

Once the subject has finished the contents of the breakfast, start a timer. Record on the visual analogue scale, do this; straight after breakfast, 30 minutes post-breakfast, 1.5 hours, and 2.5 hours after breakfast. After 90- 150 minutes post-breakfast, prepare the pasta. Cook the pasta in boiling water until cooked. Once cooked add the tomato pesto to the pan. The total amount of pasta should be 1250g, one plate having 500g of pasta and another three plates containing 250g each. Record the participants’ appetite recording on the visual analogue scale for the final time, then place the 500g plate of pasta as well as a glass of water in front of them. Instruct the participant to eat the pasta until they feel comfortably full and cannot eat anymore. Again, this process should be done in the eating booth so no variables can affect the experiment. If the participant finishes the 500g plate of pasta, replace with the 250g plate of pasta, and make sure you track the amount of pasta being consumed. Once they have finished, record the amount of pasta remaining at the end of the experiment. When repeating or duplicating this experiment, ensure patients being used don’t have any allergies, as the ingredients used contain; lactose, gluten, barley, and soya.

Study design

A two-arm cross-over study is implemented to the experiment to gather a better understanding of the satiation levels between whole fruit and fruit juice when consuming breakfast on a fasted state. Cross over studies involve having two practicals over a period of time, consisting of two sessions. For instance, we have implemented that participants will have the whole fruit in one of the practical and then the orange juice two weeks later in another practical, using the same method for both fruit types.

Measures

The effect of the orange or the orange juice on satiation will be assessed by the total amount of the test lunch consumed.
Visual analogue scales will be used to assess hunger and satiety throughout the experiment.

Results

Baseline characteristics

Table 1: Sample baseline characteristics

Baseline Characteristics	Age	Height	Weight	BMI
Mean	24.1	170.7	67.4	23.2
SD	6.17	6.31	8.96	4.82

Figure 1

Mean	Standard deviation
-51.500	164.915

Figure 2

There was no significant difference between participants hunger scores, (shown by figure 2). Furthermore, the amount of pasta eaten when consuming fruit juice compared to whole fruit only had a slight increase in weight, on average being 507g of pasta eaten, compared with the whole fruit average, being 473g of pasta eaten, (shown by figure 1). To determine if there was a statistically significant difference between the whole fruit measurement compared with the fruit juice, a paired sample t-test was conducted. The results found that there was no significant value between the whole fruit and fruit juice (t (7) = -.883 P< 0.406). To examine the effect on satiety, two practicals took place over the two weeks, as a two-way repeated-measures ANOVA was conducted. There was no clear correlation between time and fruit types as shown by this p-value F(4,28)= .970, p=.439.

Discussion

The findings from this study suggest that satiety and hunger levels of fasted participants had no significant difference when consuming either of the whole orange or orange juice as shown in both graphs. There was no evidence suggesting that appetite levels either improved or deteriorated when consuming the different fruit types.

The results didn’t support my hypothesis, as both fruit types showed no significant difference when it came to satiety and appetite levels. Participants appetites fluctuated throughout, in the time between breakfast and lunch as well as showing similar amounts of pasta consumed after 150 minutes post-breakfast (end of the experiment).

We adopted the two-arm cross-over study for our design for the experiment, as we are able to test the same participant twice, getting both the feedbacks from the different fruit types. Using the cross over design, we were able to use a lower number of participants as you are able to use them several time, in this case, using them twice for both separate practical sessions. Additionally, it allows the participants to experience one treatment (eating whole orange) and then the other, (orange juice) and they are able to come compare. In contrast, the cross over study does have weaknesses. The main disadvantage is the washout period, which can have a carryover effect which can cause the results to be come aliased. Because of the two-week gap between consuming the different fruit types, the first practicals results can be a direct effect to the results in the second practical, causing statistical bias.

Reasoning behind why the results could have differed from other studies, could be because of participants being fasted as they didn’t consume any food for 12 hours before the experiment being conducted. Green, Elliman & Rogers (1995) suggests participants fasting over 24 hours improve cognitive function when compared with a shorter period fast. This links to the current investigation, as the participants recorded all had a shorter period fast, rather than a 24 hour fast, which could have affected cognitive function when recording the visual analogue scale, thus giving unpredicted results. Furthermore, another study supports the negative effect that fasting has on cognitive function. Presenting, that participants struggled when presented with problem solving questions, especially when compared to results of participants that weren’t fasting and had consumed food before the experiment, (Pollitt, Lewis, Garza, & Shulman, 1982). Further explaining why, the hypothesis wasn’t achieved. Similarly, Hawkins, Gunstad, Calvo & Spitznagel (2016) have implied that fasting over a short period can improve cognitive function. However, the results recorded suggest improvements are much more effective over a longer time. Signifying that fasting can improve cognitive function, although it’s more effective when performed with a longer duration. Research behind to whether fasting affects cognitive function and hunger levels remains uncertain, further studies would be advised to get a better understanding as well as having a clear outcome.

The validity of the experiment can be improved. Firstly, changing the variable of participants, as the study consisted of predominantly female participants. Having an even ratio of females to males can ensure that the experiment is precise, as the sexes can differ from one another. An example of this would be that men on average eat more food than women (Rolls, Fedoroff & Guthrie, 1991). Characteristics between the genders can differ and so the results may not relate to them, in this case only women should use this data, based on the fact eight out of nine of the participants were women. Furthermore, the data used only has one male present, and he only completed the first practical, which shows the data used is inaccurate. Finally, increasing the number of participants would give accuracy and precision to the outcome. Also, having a large number of contributors then decreases the likelihood of having biased groups as well as decreasing the validity of the results.

In comparison to my results, both Pan & Hu (2011) and Flood-Obbagy, &Rolls (2009) found that hunger levels within participants would increase when fruit juice was consumed compared with the consumption of whole fruits. Stating whole foods improve satiety and prolong hunger levels because of the amount of fibre found in whole fruit compared with the fruit juices. Research shows there is a strong correlation between the consumption of whole fruit and the decrease in satiety levels within participants. Tieken, Leidy, Stull, Mattes, Schuster & Campbell (2007) discusses that whole food such as whole fruit when compared to lower viscosity foods such as fruit juice, has a more beneficial impact on reducing both hunger and appetite levels. However, in contrast to these studies, Almiron-Roig, Flores & Drewnowski (2004) suggests that there is no significant difference for satiation levels when consuming either of the two fruit types, either in solid form or in liquid form. Instead of comparing the two forms of fruit, the study implies that the timing of consumption is more important than the physical form of energy being consumed, concluding that there is no significant difference between the two forms of fruit as the same number of calories is being consumed by the person in question.

To conclude, the research done on satiety levels with different fruit types, strongly suggests that the consumption of whole fruit over fruit juice has a more beneficial factor in reducing hunger levels throughout the day. This can lead to a decrease in daily calorie intake which can progressively lead to weight loss if done with consistency over a long duration of time. An investigation would be recommended to determine which fruit type benefits appetite levels more, as the difference between whole orange and orange juice is still undecisive.

Conclusion

As research suggests, satiety when consuming whole fruit increases and pro-longs hunger over a period of time when compared to fruit juice. Although, if the person in question fasts the night before, (having at least a 12-hour period of not eating), the satiation levels from the different fruit types will have no significant difference between them. Advocating that either of the fruit types should not be consumed to benefit from either energy balance or weight loss for people with health or weight issues.

References

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Laboratory report

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Introduction