The Nutrition Diva's Quick and Dirty Tips for Eating Well and Feeling Fabulous

Which protein sources are the most filling?

Episode Summary

Does egg protein get you any further than the same amount of protein from dairy, soy, nuts, wheat, or beef?

Episode Notes

Adding protein to a meal can keep you full longer. But does it matter which kind? Plus: Is adding sugar to tart fruit any worse for you than eating sweet fruit?

Nutrition Diva is hosted by Monica Reinagel. A transcript is available at Simplecast.

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Episode Transcription

Hello there! I am Monica Reinagel and you’re listening to the Nutrition Diva podcast—where every week, we take an evidence-based look at the latest nutrition topics and trends. And this week, we’re going to explore the research on how different sources affect satiety—or, how long they keep you full.

But first, I wanted to answer an interesting question that came in this week from Pamela, who wrote:

“Is adding sugar to grapefruit the same as eating a sweeter fruit? Is there a difference between using sweet cherries in a recipe and using tart cherries plus sugar? Is one better than the other?”

This is actually a very astute question. The naturally-occurring sugar in fruit is generally given a pass. After all, the amount of sugar that you’d get from a serving of fruit is relatively modest and it comes packaged with vitamins, minerals, fiber, water, and various phytonutrients. It’s all good.

On the other hand, we’ve been well trained to regard added sugar as a dietary demon. We’re advised to limit our intake of added sugar to no more than 10% of our total calories—or less than 5% if you’re a nutritional goody-two-shoes. And thanks to updates in our Nutrition Facts labeling, you can now easily see the amount of added sugar, broken out from the amount of total sugar in packaged foods. For general nutritional wellness (as opposed to diabetes management, for example), we’re told that it’s only the added sugar number that we need to worry about.

This, predictably, has led to some food industry shenanigans. For example, right next to the regular jams and jellies, which are made with fruit and sugar, you’ll find jams and jellies that are sweetened only with concentrated fruit juice. These are presumably better for you. Because: no added sugar.

But, if you look at the Nutrition Facts labels on these products, you’ll see that, while the added sugar content is quite a bit higher in the traditional jams than in the fruit juice-sweetened jams, the total sugar content is similar. Is there a real difference in terms of how these two products affect your body? I’m not sure there is.

Another example are the popular Larabars, which are sweetened with dates. A Larabar may have the same amount of total sugar as another snack bar that’s sweetened with honey. But while the sugar in honey will be listed as added sugar on the Nutrition Facts label, the sugar from the dates won’t, because dates are fruit.

Dates, of course, are a bit of an exception in the fruit world. They are very concentrated sources of sugar. An orange, for example, has 13 grams of naturally occurring sugar. An apple has about 16. A banana has about 15. A similar-sized serving of dates, on the other hand, has 45 grams of naturally-occurring sugar.

Sweetening a bar with dates allows you to achieve a very high sugar content but still have zero added sugars—which is what we’ve trained people to pay attention to. But in terms of how these foods will be digested and metabolized, I’m hard-pressed to see a meaningful difference between the sugar in honey and the sugar in dates.

With all that in mind, let’s return to Pamela’s question. What’s the difference between having an orange for breakfast and having half a grapefruit sprinkled with a teaspoon of table sugar? If we were to print out Nutrition Facts labels for these foods, the orange would show 13 grams of sugar, of which 0 grams are added sugar. The sugared grapefruit would also show 13 grams of sugar, but 4 of those grams are added sugar. Both the orange and the grapefruit would also be delivering some vitamin C, potassium, a little fiber, and various citrusy phytonutrients. Again, I’m hard-pressed to declare that the grapefruit sprinkled with sugar is any less healthful or nutritious than the orange.

So, I’m afraid the answer to Pamela’s question isn’t as straightforward as she (or you) might have hoped. First, we need to make sure we’re comparing two similar foods and formats (for example, whole fruits, or dried fruits, or bars, or jam), But then, if both deliver about the same amount of total sugar, I think we can consider them more or less equivalent—even if one of them contains added sugar and the other doesn’t.

I realize this may strike some of you as nutritional heresy—and I have no one to blame but myself. Because I have certainly been among those beating the drum about the importance of limiting added sugars. But as these examples show, our black-and-white thinking about added sugar and total sugar might benefit from a little more nuance and common sense.

Of course, you can keep it simple and stick with the options that have no added sugar. Just be aware that products sweetened with fruit juice concentrates or dates (which aren’t considered added sugars) may easily contain the same amount of total sugar as those that sweetened with sugar or other concentrated sweeteners that do show up on the Nutrition Facts label as added sugars.

And now, let’s tackle the question of how well different protein sources fill you up.

First, let’s just quickly review the difference between satiation and satiety. Satiation refers to feeling satisfied at the end of a meal—the feeling that prompts you to stop eating. Foods that are high in fluids and/or fiber, and foods that require more chewing (which are often foods that are less processed), all contribute to satiation.

Satiety, on the other hand, is how long after a meal you stay satisfied before you start to get hungry again. And here, protein is the clear winner. Meals that are higher in protein have been consistently shown to increase satiety compared with meals that have the same number of calories but less protein.

Studies have shown, for example, that people who eat eggs for breakfast are significantly less hungry 3 or 4 hours later than those who eat cereal or bread. They also tend to eat less at the next meal. Obviously, this could be really helpful if you’re trying to manage your weight, because it may make it easier for you to cut down on your total calorie intake.

But does the kind of protein make a difference? Does egg protein get you any further than the same amount of protein from dairy, soy, nuts, wheat, or beef? Over the years, researchers have pitted lots of different types of protein against one another to see if any were superior in terms of the satiety they provided. 

The protein source that seems to come out on top most often is whey protein, which has shown greater effects on satiety than eggs, tuna, turkey, soy, and even casein (which is the other primary protein in dairy). However, if you enjoy eggs for breakfast, there’s no need to trade in your scramble for a smoothie. Egg protein still stacks up quite well against other sources. And for those who don’t want to consume animal products, both soy and pea protein appear to be competitive in terms of satiety, as well.

Remember that these sorts of studies are looking to eliminate as many variables as possible. The proteins they test are often isolated from their food source and delivered in a powdered concentrate. In the real world, however, we’re more likely to be eating beef than powdered beef protein concentrate. My point is that controlled research conditions don’t always translate neatly into our messy lives.

In terms of the effects on appetite, the total amount of protein matters at least as much (if not more) than the source. So if a certain food is more a convenient, affordable, calorie-efficient, or palatable way for you to bump up the protein, I think that is ultimately going to matter more than the relatively minor differences in its effects on your satiety.

Finally, I want you to keep in mind that these sorts of studies look at the average or median effects on a whole slew of subjects. And you, my friend, are not a statistical likelihood, but a single individual—who may or may not experience the average result. (In fact, I feel quite certain that you are well above average!) Research like this can suggest where you want to start your investigation, but it certainly shouldn’t determine where you finish it. To find out what works best for you, you’ll need to do some N-of-1 experimentation. (An “N-of-1” experiment, is an experiment with a single subject: You)

In the Weighless Program that I run with Brock Amstrong, for example, we have our members do a series of N-of-1 experiments to discover what foods and meals work best for them—both in terms of satisfying their hunger as well as what works logistically and what they actually enjoy.

For example, one day, you might top your lunchtime salad with a small can of tuna. Another day, some hard-boiled eggs. One day, you try the same salad topped with a half cup of garbanzo beans, instead. Another day, you try it topped with avocado. All these salads have roughly the same amount of calories but differing amounts (and sources) of protein, fiber, and fat. So your assignment is to take notes on how satisfied you feel when you finish each salad and how hungry you feel three hours later.

These types of experiments can tell you a lot about your own highly personalized response to different food combinations. (If you’d like a copy of the worksheet that we use for this in our program, drop me an email at and I’ll be happy to share it with you.)

For me, the unifying theme of the two topics I covered in today’s episode is that we always need to use common sense when applying dietary guidelines and research results to our individual situations. In the case of the guidelines around added sugar, for example, following the letter of the law may not always produce the intended effects. And clinical research on protein satiety may not be the final word on what kinds of protein foods will work best for you.

I look forward to your comments and questions. You can email me at or leave me a voicemail at 443-961-6206 and your question could be featured in a future episode!