A key weight-control question gets solid — and surprising — answers from recent studies 10/09/2017
Needless to say, foods that fill you up can aid appetite and weight control.
They include foods high in protein, fat, or fiber, and low in sugars or starchy, refined grain products.
Foods high in fat aren't ideal for this purpose, because it contains more than twice as many calories (nine per gram), compared with protein or carbohydrates (4 per gram).
Protein stimulates the release of appetite-suppressing hormones, while fiber slows digestion and helps stabilize blood sugar levels.
Those effects of dietary fiber extend the feeling of fullness and prevent the blood sugar fluctuations caused by sugars and starches, which can fuel appetite.
Meats and fish are rich in protein, but lack any fiber.
Most plant foods, including beans, abound in fiber, while beans, non-starchy vegetables, and whole grains can contain significant amounts of protein, albeit much less than meat or fish.
Importantly, beans, peas, lentils, and other legumes provide more protein than most other plant foods.
Two recent studies suggest that, among appetite-allaying options, beans and fish work as well or better than meat.
Let’s examine that evidence — and the generally bogus reasons why beans get dissed by some Paleo-diet advocates.
Minnesota clinical trial sees beans equaling meat
Two years ago, researchers published a trial that tested the satiating effects of a bean-based meal versus a beef-based meal (Bonnema AL et al. 2015).
A team from the University of Minnesota recruited 14 men and 14 women, and randomly divided them into two groups.
Each group ate a lunch based on one of two “loafs”, which were equal in terms of total weight, calories, and fat — but not in carb, fiber, or protein content:
- Beef-based loaf providing 26 grams of protein and 3 grams of fiber
- Bean-based loaf providing 17 grams of protein and 12 grams of fiber
The results showed that the bean-based meal matched the beef-based meal when it came to satisfying the participants’ appetites.
During the three hours that followed the meal, there was no difference between the beef and bean meals in terms of their effect on the participants’ sense of satisfaction and appetite.
And there was no difference between the two meals when it came to the number of calories that the participants in each group consumed at the next meal.
The findings support the idea that beans — which are relatively high in both protein and fiber — may rival animal protein when it comes to allaying people's appetites.
Danish trial confirms that beans rival meats for appetite control
Last year, researchers from the University of Copenhagen published the results of a larger, single-gender trial that otherwise resembled the Minnesota study (Kristensen MD et al. 2016).
They recruited 43 young men and divided them into three groups, each of which was served a meal centered around patties of different composition:
- Veal-pork patties
- Bean-pea patties
Compared with those assigned to eat the veal-pork patties, the men who ate the bean-pea patties consumed 12% fewer calories in their next meal.
And, the participants reported finding the bean-pea loaf just as filling and tasty as the veal-pork loaf.
As lead researcher Anne Raben, Ph.D., said, “The meal composed of legumes contained significantly more fiber, which probably contributed to the increased feeling of satiety.”
Dr. Rabe summarize the implications of their findings: “[They’re] … contrary to the widespread belief that one ought to consume a large amount of protein because it increases satiety … one can eat a fiber-rich meal, with less protein, and achieve the same sensation of fullness ...”.
Fish may be more filling than meat
When it comes to comparing the filling effects of different animal proteins, the results of a small a Swedish trial suggests that fish may hold an edge over meat.
Researchers from Karolinska University Hospital — a world-renowned center of diet-health research — recruited 23 younger men (Borzoei S et al. 2006).
Four hours after eating identical breakfasts, the men were assigned to eat one of two lunches that contained equal numbers of calories:
- Fish-based dish
- Beef-based dish
Then, four hours after lunch, all the participants were served identical evening meals and their food and calorie intakes were measured.
Each participants’ appetite was rated immediately before and after the meals, as well as every hour between the meals.
And, all the participants recorded in detail the foods and drinks they consumed between dinner and bedtime.
The results showed that the fish-based lunch beat the meat-based meal, in terms of reduced hunger, optimal satiety (appetite satisfaction) and reduced post-lunch calorie consumption, although the results on these scores did not reach statistical significance.
However, compared with those who ate the meat-based lunch, the men assigned to the fish-based lunch consumed fewer calories at the evening meal, and felt no less satiated.
In addition, the men assigned to the fish-based lunch did not consume more calories after dinner.
Beans' bountiful benefits: Antioxidants, minerals, and blood-sugar control
Overall, the evidence suggests that beans are beneficial for most people even when eaten frequently.
Beans provide lots of fiber, blood-sugar-stabilizing “resistant” starch, antioxidants, and substantial amounts of “incomplete” but valuable protein.
Beans can provide “complete” protein when they're consumed along with small amounts of whole grains, or with high-protein, grain-like foods such as quinoa or amaranth.
Beans also provide essential minerals, and small amounts of essential, short-chain omega-3 fatty acids.
Importantly, even though most of the calories in beans come from carbs, a large proportion occurs in the form of “resistant starch.”
As its name suggests, resistant starch passes through our upper digestive tract without being broken down, so it doesn’t get converted into blood sugar.
In fact, beans are clinically proven to stabilize blood sugar levels for hours following a meal.
Because beans counteract the unhealthful glycemic effects of sugars and refined, sugar-like starches, they're natural allies against the development of diabetes.
And, like colorful fruits and vegetables, colorful beans rank high in anthocyanin-type antioxidants, like those which provide the red-purple-black colors in berries, red cabbage, red onions, and raw cocoa.
Paleo myths about beans
Some advocates of Paleo-style diets say we should avoid beans and other legumes.
They cite the fact that beans contain lectin-type proteins, oxalates, and phytic acid, which allegedly exert significantly bad health effects.
Let's tackle these myths one at a time.
Oxalates occur in many plant foods, and beans are not especially high in them, with dark leafy greens containing about ten times more.
While the phytic acid in any plant food impairs absorption of its iron, the extent of that effect varies, and any negative health consequences appear very minor at most.
Lastly, while legumes are high in lectins compared with most other plant foods, and lectin-family proteins can be toxic, they get neutralized by thorough cooking.
And to avoid all high-lectin plant foods, you'd need to stop eating tomatoes, whole grains, eggplant, peppers, potatoes, onions, mushrooms, and winter squash.
In summary, there's simply no good evidence that our health suffers from consuming legumes — as long as they're fully cooked.
As to the alleged non-Paleo nature of legumes, a recent analysis of Neanderthal tooth plaque revealed that they ate wild legumes (Henry AG et al. 2011).
Other Paleolithic humans are believed to have eaten a more diverse diet than Neanderthals did, so it seems likely they ate legumes too, when available.
And modern hunter-gatherers who eat diets of ancient origin — such as Africa's Kung San (bushmen) people — eat a very wide range of wild foods, including legumes.
Ironically, compared with legumes, many “Paleo-approved” foods — such as nuts, leafy greens, and many common fruits, vegetables — contain as much or more lectins, oxalates, and/or phytic acid.
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- Borzoei S, Neovius M, Barkeling B, Teixeira-Pinto A, Rössner S. A comparison of effects of fish and beef protein on satiety in normal weight men. Eur J Clin Nutr. 2006 Jul;60(7):897-902. Epub 2006 Feb 15.
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