Eat Slow, Eat Less?
Study review on the effects of eating pace and energy consumed.
Spark Notes:
Eating at a slower rate can help reduce overall energy intake within a meal when eating until satisfied.
Based on the study covered, it may impact individuals with a normal BMI more than individuals who are overweight/obese according to BMI.
With that being said, both overweight/obese and normal weight groups ate less total calories when eating at a slower pace. But only the normal BMI group ate statistically significant less.
Other positive outcomes were that both groups consumed significantly more water when eating at a slower pace and ate less calories per minute.
Regardless of energy consumption, eating at a slower pace is a great skill to practice as a means to eat more mindfully, be more present during your meals and try to become more aware of your appetite and fullness cues.
When it comes to nutrition, I think we often spend too much time talking about the quantitative science of it.
By this I mean focusing on specific macronutrient, micronutrient and calorie targets.
Focusing on these are important, but it can have us thinking as if the solutions are simple mathematical adjustments.
Struggling to lose weight? Reduce calories.
Wanting to pack on mass? Increase calories and protein.
etc etc.
Here is the issue: we aren’t robots.
Yes, weight loss will be contingent on energy balance (calories in vs calories out).
But, this does not mean that just saying “eat less” is a great strategy for weight loss success.
Alternative strategies involve focusing behaviours and habits that indirectly reduce overall energy intake or increase energy expenditure. One that is often over looked, is slowing down your eating pace.
Slowing down your eating pace has been shown to be associated with better weight management and the best part is, it’s free.
With that in mind, I wanted to breakdown a paper that compared energy intake during a meal when subjects ate either fast or slow.
Additionally, this paper had two separate groups separated by weight status. “Normal” weight according to BMI and “overweight/obese” according to BMI.
The reason for this, was to investigate whether folks of different body sizes & body fat percentages had similar effects from adjusting eating pace.
When diving into this paper, the researchers highlighted that the findings for reduced energy intake from slowed eating pace have historically been all over the place.
With some research showing reductions in energy intake for both normal BMI and overweight/obese BMI groups, while one paper showed differing energy intake outcomes between these BMI groups, and one paper showing no reductions in energy intake for either groups.
Taking all of this into consideration, the study covered in this article had the largest sample size (35 for each group) and controlled for the most factors.
Making this a decent study to see how eating pace impacts energy intake in general and between BMI groups.
Let’s get to it.
Study Reviewed: Slower eating speed lowers energy intake in normal-weight but not overweight/obese subjects
This study had two groups:
35 “normal” weight subjects.
35 “overweight/obese” subjects.
This was crossover design. This is where all subjects go through both interventions with a washout period in between. This is demonstrated below.
All participants would go to the study kitchen to eat the same meal on separate days.
One day under the direction to eat slow and on the other day under the direction to eat fast.
For eating instructions between interventions, see below.
The meal served was a mixed dish of vegetable pasta. More details below.
All subjects were told eat until they were comfortably satisfied.
What was measured in both groups was duration of the meal, energy consumed (calories), water consumed (grams), energy density (kcal per G of food & water) and rate of energy intake (cals per minute).
Results
Here is a table of all the main results below.
As you’ll see, both groups did consume more total calories during the fast pace meal.
The normal weight group did have a statistically significant difference between slow and fast, while the overweight/obese group didn't.
With that being said, the effect sizes were actually pretty close.
The effect size for energy intake increase for the normal group increase was 0.22.
The effect size for energy intake increase for the overweight/obese group was 0.17.
When it comes to effect sizes, anything below 0.20 is considered a trivial effect and anything 0.20–0.49 is considered a small effect.
So I mean, you could look at this and say “there was no impact of eating pace on energy intake within overweight/obese participants.”
But… I mean.. that’s a bit of an oversimplification.
We did see an absolute increase in calories consumed and the effect size was 0.03 away from crossing the “small effect size” threshold.
Secondly, we saw an 8 % decrease in calories when eating slow for the overweight/obese group and a 10% decrease in calories when eating slow for the normal BMI group.
So this is evidence that eating pace may impact energy intake more for folks with a normal BMI, but I’m not convinced that slowing down your eating pace wouldn’t have a positive outcome in terms of at least aiding calorie reduction in higher BMI folks too. Especially if someone eats really fast.
Now, energy intake is not all that matters for health, so let’s dive into some of the other findings that were not specifically energy intake related.
Here we saw both groups did consume more calories total in the fast group when compared to the slow group. As mentioned above, only the “normal”weight group did show a statistically significant increase in energy intake from the faster eating pace.
Here we see that both groups did consume significantly more water during the slow paced meal as well. So regardless of energy consumed, increasing water intake is generally a positive behaviour and was seen in both groups.
Lastly, we see that calories consumed per minute was significantly higher when eating at a fast pace.
This is undoubtedly obvious, but I bring it up because it can be an undervalued benefit of a slower eating pace.
This was a very short term study. Meaning it can’t demonstrate long term effects.
With that in mind, if you struggle with being aware of your appetite and fullness signalling, then slowing down your eating pace will at least give you more opportunity to practice becoming more aware of these cues.
In the long run, this increased awareness would presumably only help your overall dietary behaviours. Especially if you struggle to manage energy intake.
Takeaways
I think overall, this study did show that a slower eating pace is probably a net positive when it comes to our eating behaviours.
The impact on reducing energy intake may be more pronounced in normal weight folks than overweight folks, but I still think it will only have positive results in that realm.
If anything, eating slower sure as hell won’t ramp up your energy intake, regardless of body size.
If you find yourself unable to identify your appetite signalling, then eating slower is a great strategy to become a more mindful eater.
One other caveat here is that you may have noticed the overweight/obese participants did eat noticeably less calories in both interventions than the normal weight group did.
I’m not trying to say that overweight people automatically eat more than normal weight individuals because that’s not always true, but we wouldn’t expect there to be such a difference here.
As the researchers pointed out, this may be as a result of weight stigma. Due to such rampant weight stigma within out society, overweight/obese individuals may be more self conscious while eating in public spaces. This could lead to eating less in public when compared to being alone.
The kitchen was public during this intervention, making this a potential downside of this paper.
Changing eating environments of individuals could definitely impact the outcomes of this study and that impact may have been larger for the higher BMI group.
With all of that in mind, I am a big of fan adjusting eating pace as a dietary strategy.
I think we have too much focus on intentional caloric restriction within standard dieting practices.
Focusing on external factors like making our eating environment more relaxed and conducive to being mindful, is a big area of opportunity for many of us.
And as seen here, developing portable habits such as eating slower could have positive lasting effects on your diet, relationship with food and ability to manage your weight.
Portable habit: a habit that you can do anywhere and is not reliant on having access to certain resources or being done in certain environments.
All in all, unless you are struggling with being underweight and have a hard time getting enough calories in, then I would generally suggest slowing down your eating pace as a strategy to manage intake and develop more awareness with your appetite/hunger cues.
You can start slow here.
Time a standard meal and progress from there.
If a meal takes you 10 minutes to eat, then try to add 2–5 minutes onto that at a time.
The slow eating group in this study showed overall positive effects when going from about 9 minutes to 21 minutes for the meal duration. So you could try to work up to around a 20 minute meal and see how that impacts your diet and appetite.
As for cues, I would take them directly from this paper:
—If you have no time constraint, remind yourself of that before the meal
—Chew slowly
—Take small bites
—Put your utensil down between bites
—Take a few deep breaths before the meal to try and eat in a more relaxed state
—Have a glass of water available to help drink water during the meal to potentially help you feel more full & satisfied
Add whichever cue into your meal that sticks out here and progress from here.
At the end of the day, when it comes to our health, you probably will never regret being a more relaxed, patient and mindful eater.
Cheers,
Coach Dylan 🍻
References:
1. Retrospective longitudinal study on the relationship between 8-year weight change and current eating speed
https://www.sciencedirect.com/science/article/abs/pii/S0195666311001383
2. Improvement in chewing activity reduces energy intake in one meal and modulates plasma gut hormone concentrations in obese and lean young Chinese men
https://academic.oup.com/ajcn/article/94/3/709/4411851
3. Eating Style of Obese and Non-obese Males
https://journals.lww.com/psychosomaticmedicine/Abstract/1980/11000/Eating_Style_of_Obese_and_Nonobese_Males.1.aspx
4. Bite size, ingestion rate, and meal size in lean and obese women
https://www.sciencedirect.com/science/article/abs/pii/0195666393900055
5. Slower eating speed lowers energy intake in normal-weight but not overweight/obese subjects
https://pubmed.ncbi.nlm.nih.gov/24388483/
6. A Naturalistic Study of Social Influences on Meal Size among Moderately Obese and Nonobese Subjects
https://journals.lww.com/psychosomaticmedicine/Abstract/1979/02000/A_Naturalistic_Study_of_Social_Influences_on_Meal.3.aspx