Over 100 years ago a health enthusiast named Horace Fletcher
warned us that “nature would castigate those that don’t masticate” One hundred
ears on and we live in an ‘obesogenic’ food environment characterized by highly
palatable, high energy dense foods that are often served in large
portions. These features combine to
promote energy intake, and when the foods are softly textured, they can
increase the rate of eating (g/min) and promote energy intakes even
further. The current global rates of
obesity would be enough to make Fletcher grind his teeth in disappointment!
We are told that hyper-palatable, energy dense foods rich in
sugar and fat and are ‘engineered’ to be less satiating and to encourage
consumption. These commonly come in
packaged processed foods but also in the home food environment where energy
dense Dauphinoise potatoes, tagliatelle carbonara and cheesecake can also
promote passive overconsumption. Very high levels of fat and sugar are absolute
characteristics of dessert dishes such as franigpan or baklava and are more
often home made than purchased as a prepared dish. However we may well ask, is it possible to
also apply the same rationale to reversing this trend and use the sensory
properties of foods to promote eating behaviour’s that drive satisfaction while
supporting energy intake reductions?
This is the approach being applied by a group of researchers
led by Professor Ciaran Forde at the Clinical Nutrition research Centre of the
National University of Singapore in one of their recent scientific publications[1].
The authors begin with an elaboration of the research that
they and others have done, which show definitively, that the rate at which we
eat a food (eating rate: ER) greatly influences overall meal intake. The basic unit in this regard is grams of
food per minute and is strongly influenced by bite size and the total number of
bites taken within a meal. That
determines what goes into the mouth. Thereafter, the key measures are chews per
bite and time in mouth with the longer the chewing the more satiating the food
per kcal consumed (remember what Fletcher said about ‘castigate’ and
‘masticate’). In effect this is about
bites, chews and swallows. All can be
quantified using simple behavioural coding of video recordings of people as they
eat. All available evidence shows that
the larger the portion size, the greater energy density, and the faster one
eats, the more energy is consumed within a meal. The key question posed by the
team in Singapore is whether we could use food texture to better regulate food
intake within a meal and could this offer some protection against larger
portions and higher energy density? They
opted to conduct their experiments with a traditional rice-based breakfast
widely consumed in Singapore among a group of healthy regular breakfast
consumers. The key part of the study was
to modify the texture of the breakfast to effect a change in eating rate, and
this was achieved by greater or lesser milling of white and brown rice
grains. The energy density served was
low (0.5kcal/g) or high (1.0kcal/g) and was changed by varying the amount of
both sunflower oil and the starch product, maltodextrin. In the study, the portion sizes offered were
either 700 grams or 1050 grams. Thus the effect of thickness was examined for a
given portion size when energy density varied and in the second study, the
effect of thickness was studied when energy density was held constant but with
portion size varied. The key points of the results are as follows:
Þ
Constant
portion size: Increasing the thickness of the breakfast led to a higher
bite size (about 30% higher), higher oral exposure per bite (about twice as
high) and more chews per bite (about three times higher). This was not
influenced by the energy density of the diet. The overall eating rate was
halved by the thicker porridge leading to a decline in caloric intake at
breakfast of about 75 calories
Þ
Constant
energy density: Higher portion sizes led to an increase in breakfast intake
compared to smaller portion size (487 v. 425 g). Thicker porridges led to lower
intakes than thinner porridges (425 v. 488g). The thicker porridge almost
halved the eating rate.
The bottom line is that by manipulating texture, significant
beneficial effects in caloric intake from the test breakfast were seen. Thus the options for the reformulation to
consider extend beyond portion size and energy density to also use food texture
in a way that effectively changes eating behaviour. In each case there were no differences in
post-meal hunger or fullness and the changes did not reduce palatability, if
anything in the thicker breakfast liking tended to go up. These results are encouraging at a time when
food processing is under attack and the results suggest that processing
techniques like thickening, hardening, extruding and adding ‘crunch’ can be
used to change our eating behaviours and effect a change in energy intake
without a loss in eating pleasure or satisfaction.
Food technology can help alter the characteristics of foods
such as texture and energy density to extend eating time and thus to reduce
energy intake. Here is where the rubber
hits the road. How do everyday food
choices and eating behaviours, which are often habitual and routine link up with
our internal biologic control of food intake? With the huge failure rates of
dieting with a 2-year relapse rate of about 50% and a 5-year relapse rate of
about 95% we can ask – is it possible to restrict intake long term to prevent
weight re-gain? The study described above could help to mitigate the need to
feel restricted or deprived, by re-engineering the food environment to extend
the eating time for meals and support energy reductions.
We are largely unaware of the precise energy content of the
foods we eat, and the largest variations in energy intake tends to occur within
meals in calories consumed to the onset of fullness (satiation). The present study is one of a new breed of
controlled feeding trials that highlight how a food’s sensory properties can be
used to promote fullness and show that the act of consuming a satisfying meal
is itself a strong satiation cue. Here we see the application of sensory
properties like meal texture to not only promote palatability and liking, but
also to act as functional cues to promote satiation and satiety. All this is
now possible in the modern processed food world, far removed from the original
ideas proposed by Horace Fletcher. Today, modern food processing techniques
contribute food safety, and reformulation and food processing techniques can be
applied to change energy density, and enhance the eating experience through
food texture.
My thanks to Prof Ciaran
Forde for fact-checking and editorial input.
[1]
Keri McCrickerd et al (2017) Texture based differences in eating rate reduce
the impact of increased energy density and large portions on meal size in
adults. Journal of Nutrition, March 27th.
