PORTION CONTROL FOR WEIGHT LOSS
It seems obvious, doesn’t it—bigger portion sizes means people tend to eat more. But science is never interested in what “seems obvious.” They want proof that portion size affects how much people eat.
To no one’s surprise, they got plenty of proof that larger portion sizes resulted in people eating more and gaining weight.
In the Journal of the American Dietetic Association, the title of their research paper says it all: “Increasing the Portion Size of a Sandwich Increases Energy Intake.”
By “energy intake,” they mean amount calories eaten. The study comprised of 75 young adults (37 females and 38 males) in a university setting. Researchers were portioning food--students were given lunch in a lab once a week for four weeks and were instructed to eat as much of the sandwich they were given as desired.
The study found that “the portion size of the sandwich significantly influenced lunch intake for both males and females.” When they were given a 6-inch sandwich, a majority of the students ate the entire thing.
But “when served the 12-inch sandwich, compared with the 8-inch sandwich, females consumed 12% more energy (74 kcal) and males consumed 23% more energy (186 kcals). And yet they reported no significant difference in hunger or satiety when it came to eating the 12-inch and 8-inch options.
Portion Control For Weight Loss
They concluded that dieticians “should educate their clients” about this phenomenon and provide strategies for moderating the amount of food they eat when portions are enlarged.
Researchers in Oxford and London in the U.K. were similarly interested in this phenomenon, but not just as it relates to food, but alcohol and tobacco as well. In the article, “Portion, Package or Tableware Size for Changing Selection and Consumption of Food, Alcohol and Tobacco” published in the Cochrane Database of Systematic Reviews, researchers wanted to determine and assess the influences of the “varying sizes and shapes of food, alcohol and tobacco products in environments such as shops, restaurants, bars and homes.” They also wanted to see the “effects of interventions” upon these variables.
Their review of published studies showed in general that “exposure to larger sizes increased quantities of food consumed among children and adults.” Larger tableware (plates/bottles/bowls) had a smaller effect but did increase “the quantities of food people selected for subsequent consumption.”
Portioning Food
This was true for both adults and children. The authors conclude that “people consistently consume more food when offered larger-sized portions, packages or tableware than when offered smaller-sized versions.”
Similar results were reported in the American Journal of Clinical Nutrition. In “Portion Size of Food Affects Energy Intake in Normal-Weight and Overweight Men and Women,” the researchers performed their own study of fifty-one men and women. They were given lunch one day a week for four weeks and were given free rein to select the desired amounts of the food on offer (macaroni and cheese).
The results were clear: “Portion size significantly influenced energy intake. Subjects consumed 30% more energy (676 calories) when offered the largest portion than when offered the smallest portion.” They conclude larger portions lead to overeating. They point to the fact that “portion size is a modifiable determinant of energy intake “ and should be considered in “the treatment of obesity.”
Similar results were reported in the British Journal of Nutrition with the article, “Increased Portion Size Leads to a Sustained Increase in Energy Intake Over Days in Normal-Weight and Overweight Men and Women.” In their studies, all food was divided into “standard” portion or “large” portion. Outcomes were determined by the amount of food eaten over the days of the study.
Eating Smaller Portions To Lose Weight
The authors point out that food portion size has increased “in parallel with the rise in overweight and obesity.” Food portions have increased considerably since the 1980s, particularly in the USA. “Studies have demonstrated that portions of food sold in supermarkets, fast food establishments and restaurants have steadily increased,” they point out. As a result, they hypothesize that “increasing portion sizes of food may be undermining normal appetite control and inciting over-eating.”
Why does this happen? “Consumers tend to eat what they are served,” the researchers point out, “even if it is an inappropriate amount for their energy needs.” Larger servings seem to override internal satiety cues. Were they able to scientifically prove this, though, in a study of individuals in a residential setting and not only in the lab?
Again, to no one’s surprise, they were. Energy intake (or calories consumed) were “significantly increased in the large portion size condition compared with the standard portion size condition in the whole group.” The incidence of higher energy intake occurred consistently over all meals—breakfast, lunch, and dinner.
Plus, people appetite and satiety seem to have been influenced by size portions. The result? People in the larger portion group gained weight: “There was a significant increase in body weight over the four days in both men and women in the large portion condition.”
Food Portion Control
The researchers conclude that the “availability and consumption of large food portions had a significant and sustained effect on energy intake over four consecutive days under fully controlled residential conditions.“ There was no doubt: Increased portion size affects consumption and weight.
The above UK study lasted under controlled conditions for four days. Researchers in the USA performed a similar study lasting two days and found comparable results. In the Journal of the Academy of Nutrition and Dietetics, the title of their articles says it all: “Larger Portion Sizes Lead to a Sustained Increase in Energy Intake Over Two Days.” Participants who were given larger portion sizes saw a “significant” increase in energy intake (calories consumed.)
But what happens, the researchers wondered, if larger portion sizes were offered for more than two or four days?
The same researchers who performed the two-day study extended the experiment for a longer period—in this case, eleven days. They reported their findings In the journal, Obesity. In “The Effect of Large Portion Sizes on Energy Intake is Sustained for 11 Days,” they report that, sadly, people continue to overeat when presented with larger portions.
They do not generally adjust their consumption over time. Participants—both men and women—tended to eat an additional [mean of] 425 calories per day when portions were super-sized, with no adjustment to energy output. The researchers conclude that “the results of this study extend previous findings by showing that the effect of large portion sizes on energy intake is sustained…for as long as 11 days.”
They add that “when there is a continual abundance of food, regulatory mechanisms that affect energy intake cannot be depended on to halt overconsumption even after several days.” Anyone who has ever been on a vacation can attest to the truth of this finding.
Unfortunately, these studies didn't show us "how to eat in moderation." Even though we all “know” that sustained eating of larger portions contributes to obesity, scientists were able to prove it in both controlled lab and residential settings. It’s more proof that “environmental influences such as portion size” can make a big difference.
Eating Smaller Portions To Lose Weight
Portion sizes haven’t increased as a response to growing hunger. Our hunger has increased as a response to bigger portions. The Portion Size Effect basically states, "the more food you’re served the more you’ll eat."
So, how can you start eating smaller portions? How can you start learning portion control and serve yourself smaller portions of food? There's an course for that and it used the same research studies cited below to develop its method.
Studies cited:
Rolls, B. J., Roe, L. S., Meengs, J. S., & Wall, D. E. (2004). Increasing the portion size of a sandwich increases energy intake. Journal of the American Dietetic Association, 104(3), 367–372. https://doi.org/10.1016/j.jada.2003.12.013
Hollands, G. J., Shemilt, I., Marteau, T. M., Jebb, S. A., Lewis, H. B., Wei, Y., ... & Ogilvie, D. (2015). Portion, package or tableware size for changing selection and consumption of food, alcohol and tobacco. Cochrane database of systematic reviews, (9). https://doi.org/10.1002/14651858.CD011045.pub2
Rolls, B. J., Morris, E. L., & Roe, L. S. (2002). Portion size of food affects energy intake in normal-weight and overweight men and women. The American journal of clinical nutrition, 76(6), 1207-1213. https://doi.org/10.1093/ajcn/76.6.1207
Kelly, M. T., Wallace, J. M., Robson, P. J., Rennie, K. L., Welch, R. W., Hannon-Fletcher, M. P., ... & Livingstone, M. B. E. (2009). Increased portion size leads to a sustained increase in energy intake over 4 d in normal-weight and overweight men and women. British journal of nutrition, 102(3), 470-477. https://doi.org/10.1017/S0007114508201960
Rolls, B. J., Roe, L. S., & Meengs, J. S. (2007). The effect of large portion sizes on energy intake is sustained for 11 days. Obesity, 15(6), 1535-1543. https://doi.org/10.1038/oby.2007.182
Rolls, B. J., Roe, L. S., & Meengs, J. S. (2006). Larger portion sizes lead to a sustained increase in energy intake over 2 days. Journal of the American Dietetic Association, 106(4), 543–549. https://doi.org/10.1016/j.jada.2006.01.014