Friday, February 25, 2005

How energy densities of food can help you lose weight

What are energy dense foods? What can they do for me ?



Low energy dense foods are those foods that are often high in micronutrients, but low in calories, per gram of food. Prime examples of foods that have low energy densities are lettuce and watermelon. These foods are typically very high in water content and fiber and usually refer to fruits and vegetables(4), but could also include manufactured foods such as artificial sweeteners which contain less calories per gram than normal sugar(3).

It has been well publicised that eating low density fruit and vegetables may help you to lose weight, and it has implications for the way in which the weight loss industry deals with the problem of obesity. The theory behind eating low energy dense foods, assumes that you can eat a mound of lettuce and watermelon and still consume less calories than if you had consumed 1 cream biscuit. Eat more and consume less calories. Research also supports the idea that diets low in energy density and palatability (how it tastes) can be a significant determinant of how many calories you consume, irrespective of the fat content.(5) What this means is that all those low fat versions of food you buy in the supermarket, may be pretty useless unless they contain less actual energy or calories than their full fat equivalent. One study suggests that even if a meal is high in fat but composed of mostly vegetables, it can be relatively low in calories per gram of food eaten and therefore have a low energy density.(1)

There are differing views as to whether low energy dense foods promote feelings of fullness, and are as satisfying to eat as their high energy equivalents e.g. lettuce versus cream biscuit. McCrory et. al. (2000) identified as mentioned above in their review, that there is a relationship between how the food tastes, the energy density of the food and total energy intake. They cite that in numerous unpublished studies "pleasantness of taste is positively associated with the energy intake of single foods.", that is if it tastes good, more than likely, you'll end up eating more of it and therefore more calories. Of course, in reality, this may vary from individual to individual.

There are however, some studies that support the theory that low energy dense foods are satisfying. Eating foods such as salads, for example before or with a meal of any size have been shown to promote feelings of fullness and reduce the amount of food eaten overall (2). Of course, for those who eat cheese and salad dressings with their salads, the calories will obviously be increased.

Consuming foods with high energy density can result in consuming too many calories without even knowing it, and still be hungry for more food. These foods, typically, the french fries, are very high in energy, but obviously low in vitamins and minerals, may be satisfying at the time of eating, but perhaps a 1/2 an hour or an hour later, you may be hungry for more food. So while you've eaten a lot of calories with the french fries, and you're hungry again so quickly, the likelihood of weight gain is probable if food such as french fries are included in the diet regularly.

In short, low energy dense foods are those that contain high amounts of water, and can be consumed with a relatively small amount of calories. What this means is that you can incorporate more of these foods into a balanced diet to get a more food for your calorie budget.

What are foods that have relatively low energy densities ?

You may also be able to guess which foods have low energy densities by how much water and fiber the food contains. If you know it to contain alot of water, then it is likely that it has a low energy density.

So if you ate 100 grams of watermelon, you'd be consuming 23 calories. If you ate 100 grams of raw unpeeled apple, you'd be consuming 55 calories (over double the calories). You can see the difference. You can engineer a weight loss strategy to consiously consume less calories while consuming the same amount of food that you'd normally take in.

Sample Meal Plans With Low Energy Densities and High Macro-nutrient intakes follows:

Breakfast

100 grams unprocessed bran
low fat milk
low fat desert yogurt

Total calories: 321 calories

Compare this with eating corn flakes, low fat milk and yogurt - 549 calories


Morning Tea

50 grams rockmelon
50 grams watermelon

Total calories: 22.5

Compare this with having a meusli bar - 124 calories.

Lunch

2 slices of wholemeal bread
Avocado spread
Canned tuna
Lettuce

Unpeeled nashi pear

Total calories: 167 calories

Compare this with eating a chicken and lettuce white sandwich with margarine, you'd be consuming about 178.70 calories.

Afternoon Tea

2 raw carrots and 5 slices of fat reduced cheese

Total calories - estimate around 122 calories

Compare this with eating 1 meusli bar - 124 calories.

Dinner

Lettuce, cherry tomatoes and avocado

Grilled Salmon
Mixed Vegetables
Brown Rice
Seafood Sauce

Water

Fruit salad

Total calories - about 494.20





Compare this with eating mince, pasta and a pasta sauce of the same meal size which totals to about 523 calories. Notice in the above dinner menu, a first course, main meal, drink and desert has been included for less calories than that eating a serving of spaghetti bolognaise.

Total calories for low energy density menu is 1,126.70 for the day.

Total calories for the alternative menu is 1,498.70 for the day, which makes a total calorie saving of 372 calories - eating the same amount of food, just watching the foods that have a higher amount of calories per gram of food.

So now you've got some idea of how to develop a low energy dense diet, don't go away and decide to eat only low energy dense foods ! Dietary energy density is only one factor that influence overeating and obesity. There are many other factors that influence a healthy diet. See the diagram here Nutrition.org The diagram illustrates that while energy density is important it is only one factor needed to be implemented to maintain a healthy diet and therefore a healthy, normal weight body.

The diagram emphasises that energy intake is influenced by the amount of processing the food has undergone, the glycemic index, energy density, palatability, portion sizes and variety within the food groups.

While its great to pay attention to the energy density, also look out for these other factors. One food group should never be neglected and eating a variety of foods is beneficial in weight loss.(5) I am not saying never eat foods that have higher amounts of calories again, you can often combine foods with low amounts of calories with other foods high in calories to give your body the nutrients it needs.

So eat a variety of foods, and work out which foods have less energy per gram of food and which ones are more energy dense. Eat foods with less energy density first, or eat them with foods that have higher amounts of calories.

References:

(1) La Fontaine HA, Crowe TC, Swinburn BA, Gibbons CJ. Two important exceptions to the relationship between energy density and fat content: foods with reduced fat claims and high fat vegetable-based dishes.

(2) Rolls BJ, Roe LS Meengs JS. Salad and satiety: energy density and portion size of a first course salad affect energy intake at lunch.

(3) Drewnowski, A. Intense sweeteners and energy density of foods:implications for weight control. Eur J Clin Nutr. 1999 Oct;53(10):757-63.

(4) Rolls BJ, Ello-Martin JA, Tohill BC. What can intervention studies tell us about the relationship between fruit and vegetable consumption and weight management ? Nutr Rev. 2004 Jan;62(1):1-17.

(5) McCrory MA, Fuss PJ, Saltzman E, Roberts SB. Dietary Determinants of Energy Intake and Weight Regulation in Healthy Adults J Nutr 2000;130;276S-279S.

The Full Article with Food Nutrient Values can be seen here