If you want to lose weight and keep it off, you must control hunger. The goal needs to be maximal hunger suppression with minimal calories. This blog teaches you the science and take homes on how to accomplish this.
If this is your first time reading a Metabolic Effect blog, and you hate science, then please skip down to the take-home section where you can quickly get the bulleted behavior changes we recommend based on the science discussed here.
The feeling of filling up from a meal is controlled by stretch receptors in the stomach and hormones. Both signal the brain it is time to stop eating. This short-term hunger alleviation is called satiation.
Satiety is the ability to feel full and satisfied over the long-term.
Satiation and satiety have taken a back seat in the nutrition world to things like glycemic index, insulin load and antioxidant concentrations in foods. This is a shame, because your ability to get, and stay full is directly related to your ability to make the right choices at your next meal, and the rest of the day.
What you eat at one meal directly impacts how much you eat, what you will crave, and how soon you will want to eat your next meal. Your meals are not mutually exclusive; this a critical understanding.
Controlling your hunger is THE most important aspect of creating a diet that works for you. If you can't get and stay full, you will keep eating, mostly the wrong things, until you do.
Another piece that needs mentioning is satisfaction. I am using the term, satisfaction, to distinguish the purely hunger elements from brain related cravings, both behavioral and biochemical.
We all know that feeling full does not necessarily equate to a desire to stop eating. You can be full, but are you "dessert full?" The desire to taste certain things like sweet, salt, fat, etc., leans more toward a discussion of cravings. I have written many blogs on this, and will, again, review cravings here. Obviously hunger and cravings are closely linked, and overlap significantly.
Recently, I acted as part of a panel of experts tasked with finding a "metabolic index" for foods. Basically, we were being asked to define the most important characteristics of foods to develop a "metabolic ranking system."
Two things became very apparent during this discussion. First, even the experts disagree on the importance of these different factors of nutrition. Second, many of these top experts are woefully misinformed about the science of satiety.
Here is the ultimate point I think everyone misses. A healthy, low calorie, nutrient dense meal is none of these things if, as a result of eating the meal, hunger and cravings for high calorie junk food occur later.
It is critical to understand that what is eaten, or not eaten, at one meal is directly related to what is craved, and how much is eaten, at the next meal.
Spend just one week in a weight loss clinic and you will immediately see the futility of prescribing diets based strictly on the health attributes of food. If people don't like what they are eating, and if their food does not satiate and satisfy them, then they have almost zero chance of success.
Metabolic Effect is known for its evidence based approach to metabolism. When my brother and I started this company, we had the idea that when people know better, they do better.
Science can go along way in telling us what is most likely to work, but there has always been, and always will be, individual reactions that contradict the science. This is the art of metabolism, and I encourage you to always honor your individual reactions to food over what the science says. You know your body better than I do, and better than any research study does.
So please, after reading this blog, take a structured flexibility approach. The science (taken from multiple review articles and documented throughout) should be your structure. That is where to begin. But, then be flexible in honoring your own body's responses. You may indeed vary somewhat since science is about averages, not individuals.
Research is pretty clear on how different macronutrients impact hunger. This is blatantly, and falsely, communicated by many experts and bloggers. The vast majority of studies show that the hierarchy of macronutrients, in terms of suppressing hunger, goes like this: protein is better than carbs, which is better than fat. (See Very Recent Review Study Here)
Read that again. Fat is last, not first!! That is not my opinion, that is what the science tells us.
I realize this comes as a shock to many people reading popular paleo, primal, and keto blogs. Fat is the LEAST satiating of the macronutrients. Multiple research studies, over years, confirm this fact.
Protein reigns supreme as the ultimate hunger fighter. Again, research is VERY clear on that. There is a little less certainty when it comes to carbs compared to fat. Most studies show carbs are better than fat, but there are more than a few that show the opposite (this likely has to do with fiber content of the carbs studied, as fiber is also very satiating).
So the data leans very, very strongly towards fat being the worst macronutrient for controlling hunger.
Fat also contains more than double the energy of an equal amount of protein and carbs. Fat is also the least thermogenic of the macronutrients. In other words, in terms of fat storing potential of macronutrients (meaning, how likely it will contribute to calorie excess and fat gain), the same hierarchy for satiation holds true as for fat storage. When single macronutrients are considered, protein is least likely to be stored, carbs next and fat most.
This becomes more complicated when you consider low carb diets and very low carb diets (i.e. ketodiets). There is still much debate, and I will get into the science in a minute, but, just understand, these diets are almost always higher in protein, and protein and fat are VERY satiating in combination. As a result, these diets almost always end up being lower calorie diets than the diets they are compared against.
Of course macronutrient combinations matter since we don't typically eat food in isolation. These combos support the idea that adding either fat or carb to protein elevates the satiating potential. Additionally, adding fat and carbs increases satiation, but this may not be much help since this combo is very calorie dense, AND may cause cravings for more calorie dense foods later. (SEE THIS BLOG)
So, what about all the talk in paleo, primal and keto circles about how satiating fat is? Well, almost all low carb, high fat diets are higher in protein than the high carb diets they are compared against.
When protein levels are held constant, the data shows it is the protein content of these diets, NOT the fat content providing the effect (see study here). That particular study, by the way, is one of the only that looked at this problem by equalizing protein levels in the compared diet. I suggest you read it if you really want to understand this issue.
Another issue is ketones versus fat. Ketones may indeed be very hunger suppressing. However, fat and ketones are not the same thing. It takes 10-30 days for the typical person to "keto adapt." At that point, these high fat diets do seem to become hunger suppressing. That is from the ketones, but again, ketones are NOT fat.
I am not aware of any studies looking at the ketone versus protein contribution to satiation once someone has "keto-adapted." Given people will need a protein content below 20% to reach ketosis, and the studies of ketone on hunger that do exist show hunger suppression, we MAY be able to safely say ketones are on par with protein in their ability to satiate? But, this remains an unknown.
Let's get back to fat versus carbohydrates, and carbs in general. Part of the issue with varying effects of carbs may be the amount, and type of fiber they contain. High amounts of soluble and viscous fibers are shown to have a powerful hunger suppressing response.
The fibers that seem to provide the most benefit are viscous in nature. Viscosity refers to the thickness and gel-like nature of the fiber. These types of fiber coat the digestive lining interacting with L & K cells, which then signal, through hormones like GLP & GIP, to turn down hunger. (SEE THIS BLOG)
In fact, one recent review in 2013 showed that these may be the only types of fibers that do aid hunger. They include things like B-glucan from oats, psylllium, glucomannan, guar gum and pectins from things like apples.
This is one of the reasons you will find these fibers exclusively in our Craving Cocoa product.
The take home here is to add fiber, as a priority, along with protein for maximal hunger suppression with lower calorie load.
The goal of any meal should be to fill up quickly (satiation), and stay full for as long as possible (satiety) with the least amount of calories possible. This is why protein and fiber, in combination, MAY be better than protein and fat or starch.
Now we get to one of the most fascinating and least talked about aspects of hunger. It also may be the most important.
Before you even put food in your mouth, you are making assessments and determinations that will impact its ability to satisfy you. Is it liquid? Is it solid? What does it smell like? Is it on a very large plate or a small plate? In what context is the food being eaten? Are you by yourself watching TV or at the movie theater watching a movie with friends?
The Chambers, et al. review, "Optimizing Foods For Satiety," published in the journal: Trends in Food Science & Technology volume 41 2015, summed it up this way:
"even before food arrives in the gut, cognitive and sensory signals generated by the sight and smell of food, and by the oro-sensory experience of food in the oral cavity will influence not only how much is eaten at that eating episode (satiation) but also in the period after consumption (satiety)"
Once you begin chewing a food, its texture has a large impact. Solid foods are more hunger suppressing than liquids. Viscosity, creaminess and other factors effect how impactful the food will be on hunger as well.
The "mouth feel" of a food is important, and conveys information about the probable nutrient density of the food. This is sometimes referred to as the cephalic phase response, or the neuro-lingual response.
In the world of texture and hunger, the hierarchy appears to goes like this:
solids > viscous liquids > creamy liquids > regular liquids.
In one study, adding air to amplify volume in a milkshake preload, while keeping calories constant, caused a 12% calorie reduction at the next meal. We took advantage of this study in the formulation of our Craving Shake meal replacement. When you consume it you will notice the airy, creamy and viscous textures. We incorporated them all to enhance the hunger suppressing action.
These effects, of texture and volume, may have much to do with the degree of chewing that is necessary. Many studies examined chewing, and it does, indeed, reduce food intake. The longer you chew a food, the more satiating it becomes.
The Chambers, et al. review sums up the research on chewing like this:"
"chewing has been associated with satiety-related cognitions (Forde, van Kuijk, Thaler, de Graaf, & Martin, 2013), preparatory cephalic phase responses (Li et al., 2011) and appetite peptide release (Katsuragi et al., 1994 and Li et al., 2011), but relationships with satiety signals are not always reported (Mattes and Considine, 2013 and Teff, 2010)."
To drive this discussion home, one more aspect of hunger needs attention: The context of consumption, and the belief about what is consumed.
It is clear, through research, that what you believe about a food will determine how that food impacts you.
In one of the most fascinating studies I have ever read, researcher, Alia Crum, and colleagues, gave participants two different milkshakes, and then measured their hunger responses including the hunger hormone ghrelin.
One shake was labeled similar to this, "620 calorie indulgent milkshake." The other shake was labeled a lot like this, "120 calorie sensible diet shake."
Sure enough, people consuming the 620 indulgent shake saw a bigger reduction in hunger and their ghrelin levels fell to levels expected with a high calorie meal. The other group saw less hunger suppression and ghrelin did not respond to near the same degree.
The amazing thing was that the shake was the same in both groups. Only the label, and description were different. If that does not make your eyes pop out of your head and the word, "WOW," come out of your mouth, it should. This tells us there is a lot more going on behind the scenes related to hunger than we know, and food perceptions are not just a small factor but a HUGE one.
One interesting thing to note is that the body is smart, and the effects of texture, volume and perception may not last past a few exposures if the body does not get the nutrients it expects. Some research strongly suggests that giving foods to "trick" the body in this way may not hold their impact if they don't also come along with the expected nutrition, natural texture and volume rich foods would have.
The ideal scenario is to eat foods that have the textures, contexts, volume, and perception of nutrient rich foods, and are actually rich in nutrition as well.
Obviously, I have picked on fat a little. I do so, not because I am anti-fat. On the contrary, fat is required, and likely, a better bet than carbs for most people (this is debatable). But, the science does not support the notion that fat is good for hunger.
This make sense in light of the volume, belief and contextual elements described above. Here is how the Chambers et al. research summed up the findings on fat in relation to carbs on satiety:
"A high fat food will often be smaller in weight (and volume) than a high carbohydrate (or protein) food of similar energy and this difference may affect the timing of the processing of the nutrients in the gut and also consumer beliefs about the likely consequence of consuming that food. That is, people tend to believe a small serving of food will not be enough to satisfy their hunger regardless of the energy it contains and these satiety expectations are thought to play a key role in eating behaviour."
I know reading blogs like this can be daunting for those who don't love science, but a key belief of ours, here at Metabolic Effect, is that: when you know better, you do better.
Now you know why choosing foods for hunger suppression is so key.
Eat foods rich in protein and fiber that are solid in nature and require plenty of chewing for most of your meals. Make sure you take the time to chew. Think: salad and chicken. To that base, add a small sprinkling of salt, fat, starch, sugar; and/or alcohol so that your food is also satisfying. When required, use functional foods, bars and shakes that are rich in thick, viscous, creamy and airy textures.
Do all this, and you will have the science of satiation, satiety and satisfaction working with you.
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