What can we learn from the Satiety Index about the effects of different food properties on how filling a food will be?
Increasing the Fat Ratio of a Food Decreases its Satiety Index Score And Makes It More Fattening.
Boiled potatoes have the highest satiety score, at 323%, however french-fries have a much lower score of 116%.
This confirms what we already know; that increasing the fat ratio of a food, reduces it’s satiety dramatically.
It confirms that we can be confident that if there is a lower fat version of any food available of any type of food, we should take it if we wish to feel fuller for fewer calories.
Even if more sugar has been added to the lower- fat food option, the sugar will have a greater effect on satiety than the higher fat content would have.
You can find tips on how to decrease the fat content in your diet in my post, ‘Ten Ways To Reduce The Fat Content Of Your Diet.’
Soluble Fibre and Protein are the Winners for Short –Term Satiety but Protein May Be the Winner for Long-Term Satiety.
In this study, the high soluble fibre content of the potatoes and fruit has outweighed in importance for satiety, the lack of protein, when their satiety scores are compared to most of the protein foods.
However, fish has a dramatically higher satiety value than other protein sources; 225%, compared to beef’s 176% and it is higher than all the other high scoring carbohydrate foods.
Ling Fish is a low-fat protein and this suggests that the other protein foods on the list would have much higher satiety scores, if low-fat versions of these foods were used, i.e. beef with the fat cut off or low-fat cheese.
We could extrapolate that other low fat protein sources would have high satiety scores, such as chicken with the skin removed, turkey mince and shell fish.
However, potatoes with their complex carbohydrates and high soluble fibre content, do come in as the winner, scoring a lot higher than fish.
This might suggest that soluble fibre content outweighs in importance for satiety, protein.
However, protein may in fact keep you fuller for longer than potatoes would.
In the BBC TV programme; ’10 things you should know about losing weight’; an experiment was conducted to show which foods kept people fuller for longer:
3 breakfasts were prepared with the same number of calories, for 3 men
Mick had a carb rich breakfast (10% more carbs).
Willie had 10% more fat.
Charlie had 10% more protein.
The 3 men were asked to rate how hungry they felt every hour on the hour.
After 4 hrs, the results confirm that Charlie felt fuller for longer and research shows that Charlie is also more likely to eat less at lunch.
This experiment measures longer term satiety than the study which was used to compose The Satiety Iindex.
Suzanne Holt, the study’s author says ‘Although most foods with high Satiety Index scores kept fullness relatively high for the whole two hours, there were a few exceptions. The fruits were served in very large portions, but fullness dropped off quickly towards the end of the second hour, reflecting the rapid rate of gastric emptying (oranges and apples and grapes are mainly sugar and water),” she adds.
She says that most foods with high Satiety Index scores kept fullness high for the whole two hours, which we can take to mean potatoes and the protein foods; fish, beans, beef, eggs, cheese and also porridge, whole-meal bread and popcorn.
I haven’t found evidence yet about the longer term satiety of these higher scoring carbohydrate foods, but we do know from studies, such as the one I have just mentioned above that protein is generally more effective for long-term satiety than carbohydrate foods.
Also, excess protein calories are lost in the process of digestion, so I could not say with absolute certainty, that potatoes are the absolute best foods for satiety and weight loss.
I can say with certainty, however, that they are very high contenders and may be on a par or even better than protein foods when it comes to satiety and weight- loss.
Effects of Soluble and Insoluble Fibre on Satiety.
There are dramatic differences in satiety scores between the different carbohydrate foods in the index.
So what food property is accounting for these differences?
Examining the correlations between soluble and insoluble fibre and satiety, indicates strongly that it could be the fibre content that is affecting their varying satiety scores.
Fibre content given in grams per usual serving size.
Insoluble Fibre Soluble Fibre Satiety Score
Potatoes : 1.6 2.2 323%
Porridge 3.0 1.3 209%
Orange 2.0 1.3 202%
Apple 0.7 2.3 197%
Wholegrain Bread 2.8 0.08 154%
Lentils 3.9 0.6 133%
White Pasta 0.8 0.03 119%
Bananas 0.7 0.6 118%
Cornflakes 0.5 0.0 118%
White Bread 0.5 0.03 100%
We can see, first of all, that there is a definite correlation between decreasing soluble fibre content and satiety score, apart from apples, which are higher in soluble fibre content than the top three satiety scorers.
This anomaly might be due to potatoes being a complex carbohydrate and oranges having a higher water content.
But otherwise, there is a clear correlation.
The correlation is not so clear for the insoluble fibre content, indicating that soluble fibre content is more important, when it comes to satiety.
However, it does clearly have an effect. When we compare wholegrain bread to white bread, it has a significantly higher satiety score, despite it having a very similar soluble fibre content.
Also, lentils have a similar soluble fibre content to bananas, but a much higher insoluble fibre content and a correspondingly higher satiety score.
Energy Density and Satiety
Although differing energy densities may account for a few anomalies in the trend between fibre content and satiety, the energy density of foods does not appear to have the same power to affect satiety as does fibre and protein content.
This is evidenced by the low satiety scores for ice-cream and yogurt (both of which are fairly low energy-dense foods).
Conclusions
Soluble fibre and protein are the most important food properties, when it comes to increasing satiety, in the short term at least.
Insoluble fibre content also has a significant effect, though less so than protein or soluble fibre.
So which other foods have high soluble fibre content and would therefore be beneficial for weight-loss?
Sprouts, broccoli, onions, carrots, peas, chick peas, strawberries, mushrooms.
Viscosity Effects
For the low scoring, non-fibrous, low-protein carbohydrate foods in the index, the difference in satiety scores between them seems to be due to their fat content, rather than their energy density.
Surprisingly, cookies and crackers score higher than yogurt, despite having a higher energy density or fat content.
This could be accounted for by the effects of a foods viscosity.
Dry foods, such as cookies are more satiating than moist foods like donuts. Foods with high moisture binding capabilities such as cheese, porridge and potatoes can also increase viscosity of stomach contents.”
Top Tips From the Lessons Learned From The Satiety Index
1.) Aim to base meals around potatoes (best choice) or wholegrain bread, rather than white bread or pasta.
2.) Always include protein in the meal, preferably a low-fat protein source.
3.) Reduce fat content, wherever possible.
4.) Include as many fibrous vegetables in meals as you can creatively incorporate.
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