Is there any high quality evidence for the importance of caloric density for weight loss dieting in humans?
Sure. The principle of caloric density is actually mentioned in the 2010 dietary guidelines for Americans released by the US department of Agriculture (16)
"...a growing body of research has begun to describe overall eating patterns that help promote calorie balance and weight management. One aspect of these patterns that has been researched is the concept of calorie density, or the amount of calories provided per unit of food weight. Foods high in water and/or dietary fiber typically have fewer calories per gram and are lower in calorie density, while foods higher in fat are generally higher in calorie density. A dietary pattern low in calorie density is characterized by a relatively high intake of vegetables, fruit, and dietary fiber and a relatively low intake of total fat, saturated fat, and added sugars. Strong evidence shows that eating patterns that are low in calorie density improve weight loss and weight maintenance, and also may be associated with a lower risk of type 2 diabetes in adults." (page 29)
"calorie density may help to reduce calorie intake and improve body weight outcomes and overall health." (page 32)
Click the link above if you want to read the entire 112 page article. :)
Here are some scientific papers:
Unless mentioned otherwise, these dietary studies allowed participants to eat ad libitum-as much as they wanted.
Epidemiologic or proof of concept studies supportive of the principle of caloric density:
1) "Dietary energy density is associated with obesity and other biomarkers of chronic disease in US adults." Vernarelli J et al; Eur J Nutr. 2014 Mar 25. (14)
In this wide scale survery of 9,551 adults, caloric density was correlated with obesity with a linear trend between increasing caloric density and both waist circumference and body mass index along with fasting insulin in women.
Several other large epidemiologic cross sectional studies have revealed a similar effect (19, 20, 21)
One of these studies suggests that water content in the primary factor (20)
2) "Variations in Cereal Volume Affect the Amount Selected and Eaten for Breakfast."; Rolls BJ et al; J Acad Nutr Diet. 2014 Mar 19. pii: S2212-2672(14)00104-X. doi: 10.1016/j.jand.2014.01.014. (15)
In this study, the investigators crushed a wheat flake cereal to create smaller galkes so that the cereal would become more compact. When subjects consumed the crushed flakes, they consumed a smaller volume of cereal but still consumed more calories (358 Calories vs 286 Calories for the standard flakes). Of course, crushing the flakes did not change the caloric density, but these results argue that even the volume of presentation can effect caloric consumption. Diagram to your right.
3) "Ghrelin and peptide YY increase with weight loss during a 12-month intervention to reduce dietary energy density in obese women." Hill BR, Rolls BJ, Roe LS, De Souza MJ, Williams NI.Peptides. 2013 Nov;49:138-44. doi: 10.1016/j.peptides.2013.09.009. Epub 2013 Sep 25. (22)
In this study, women treated with a low caloric density diet exprienced reductions in ghrelin, a neuropeptide which acts on the hypothalamus to stimulate hunger.
4) "Assessment of satiety depends on the energy density and portion size of the test meal."; Williams RA, Roe LS, Rolls BJ.Obesity (Silver Spring). 2014 Feb;22(2):318-24. doi: 10.1002/oby.20589. Epub 2013 Sep 23. (23)
In this study, 46 women were fed pasta for lunch on multiple consecutive days. The pasta was either lower or higher in caloric density (1.25 or 1.66 Cal/g). The higher caloric density pasta led to greater total caloric intake by an average of 153 Calories. Eating a salad prior to the pasta reduced Caloric intake of the pasta by 128 Calories on average. A larger served portion size also influenced caloric intake upwards.
5) "Comparison of three methods to reduce energy density. Effects on daily energy intake." Williams RA, Roe LS, Rolls BJ.Appetite. 2013 Jul;66:75-83. doi: 10.1016/j.appet.2013.03.004. Epub 2013 Mar 19.
This study looked at different strategies for reducing caloric density, either by decreasing fat, increasing fruit and vegetables, or adding water. These strategies were all effective, decreasing average total caloric intake by 396, 308, and 230 Calories per day respectively. This study supports the idea that multiple strategies can be employed to reduce caloric density successfully.
6)"Weight maintenance 2 years after participation in a weight loss program promoting low-energy density foods."; Greene LF, Malpede CZ, Henson CS, Hubbert KA, Heimburger DC, Ard JD. Obesity (Silver Spring) 2006;14:1795–801. (48)
This was a follow up study of the EatRight weight loss program. 78% percent had continued weight loss, stable weight, or regained <5% of their body weight. Those more successful at maintaining weight loss did not have lower overall food intake but consumed fewer calories (suggesting lower caloric density of the diet)
"Our results indicate that low-energy-density eating habits are associated with long-term weight maintenance. Those who maintain weight after the EatRight program consume a low-energy-density dietary pattern and smaller portions of food groups potentially high in energy density than those who regain weight."
6) "Energy density of foods affects energy intake in normal-weight women." Am J Clin Nutr 1998 67: 412-20; E A Bell; BRolls (53)
In this study at Penn State, 18 normal weight women participated in three different three day dietary studies: on in which they would consume low caloric density foods, a second in which they would consume medium caloric density foods, and a third in which they would consume high caloric density foods.
Over the study, the average amount of food consumed by mass was remarkable similar in all three groups:
However, the total caloric intake was different, with caloric density driving total caloric consumption:
This study exemplifies a simple idea. There are only two ways to reduce total caloric intake: reduce total food intake by mass or change the type of food you are eating such that it is lower in caloric density.
Clinical trials supportive of the principle of caloric density:
1) "Dietary energy density in the treatment of obesity: a year-long trial comparing 2 weight-loss diets." Ello-Martin JA, Roe LS, Ledikwe JH, Beach AM, Rolls BJ.Am J Clin Nutr. 2007 Jun;85(6):1465-77. (34)
This is a one year dietary counseling randomized study on 97 obese women. On group was counseled to reduce fat intake (RF), and the other groups was counseled to reduce fat and increase water rich foods (RF + FV), particularly fruits and vegetables. The RF + FV group ate more total food volume, consumed a lower caloric density of food, and lost [modestly] more weight, and reported more satiety on average.
2) "Subjective satiety and other experiences of a Paleolithic diet compared to a diabetes diet in patients with type 2 diabetes." Jönsson et al; Nutr J. 2013 Jul 29;12:105. doi: 10.1186/1475-2891-12-105
In a small study on the paleolithic diet in individuals with type II diabetes (12), the "paleolithic" diet was compared to a standard "diabetes" diet. The "paleo" diet consisted of "lean meat, fish, fruits, vegetables, root vegetables, eggs and nuts" and produced equal reported satiety despite lower total calories on average. Three men and ten women participated in the study which had a randomized cross-over design. The authors note that the "paleolithic" diet had lower energy density (calorie density). Compared to the standard diet, patients on the paleo diet were more likely to lose weight but more likely to complain about difficulty adhering to the diet, largely due to the elimination of wheat based products.
3) "Reductions in dietary energy density are associated with weight loss in overweight and obese participants in the PREMIER trial" Am J Clin Nutr. 2007 May;85(5):1212-21..Ledikwe JH1, Rolls BJ, Smiciklas-Wright H, Mitchell DC, Ard JD, Champagne C, Karanja N, Lin PH, Stevens VJ, Appel LJ. (46)
In this study, 810 individuals with hypertension and prehypertension were randomized to different dietary counseling groups. The group receiving traditional hypertensive dietary advice in addition to the "DASH" diet had the greatest reduction in weight loss and the greatest reduction in average caloric density reduction.
The DASH diet (Dietary Approaches to Stop Hypertension encourages consumption of fruit and vegetables (9–12 servings/d) and low-fat diary products (2–3 servings/d) and a reduced intake of fat (<25% of energy). The association between caloric density and weight loss is shown in the scatter plot as shown.
" These data indicate that weight loss over 6 mo was related to the change in the energy density of the diet. "