My guess why potatoes creates weight loss
It's not one thing, it's many things
After losing ~7lbs in 12 days with a mostly-potato diet, I've started creating a model in my head why this works for me and many others, based on my personal experience and reading.
Why does the mostly-potato diet work for many?
When you look at Slime Mold's mostly-potato diet experiment results, a consistent pattern you see is potatoes suppress appetite and cravings in a way that sounds similar to people on Ozempic. You also see a lot of weight loss with a fairly high effect size.
Potatoes also induce a higher body temperature and 'burnoff flashes' of body heat, which points to increased Non-exercise activity thermogenesis (NEAT). You consume about %10 more calories by existing for every 1C hotter your body is. NEAT is a powerful consumer of calories.
I believe it's multiple factors working together to achieve these total effects, it's not "one thing" about potatoes. Some effects work stronger or not at all depending on the individual, but since there are so many within a mostly-potato diet, it creates a high effect size.
Potatoes don't have a lot of iron
Dietary iron supplementation is associated with increased appetite. A mostly potato diet is a low-iron diet.
Potatoes are high in potassium
A diet experiment with high potassium shows some effect according to slime mold's trials. High salt intake shows a decrease in bodily lithium, which is known to increase body weight in people. I believe the high potassium in potatos probably has a similar effect.
Potatoes are low in protein and low in BCAAs
Brad Marshall has a YouTube series showing how this combo leads to an upregulation in metabolism. I think you can also show this potentially with the potato diet based on upregulated temperature alone.
Potatoes induce more GLP-1 generation
GLP-1 is created during digestion in the body and quickly cleared. The innovation of Ozempic / GLP-1 drugs is modifying GLP-1 to not be cleared quickly.
I'm guessing potatoes induce GLP-1 creation continuously in the body during digestion in various stages due to the various substances inside them. Some of the substances might induce appetite suppression through other mechanisms too.
Trypsin inhibitors
Potatoes contain Trypsin inhibitors. They have shown potential in modulating satiety hormones such as cholecystokinin. Trypsin inhibitors also inhibit protein digestion, potentially making the potato diet lower in protein than it looks. (study)
Resistant Starch & Short Chain Fatty Acids (SFAs)
Potatoes regenerate resistant starch once refrigerated over a day, which is known to suppress appetite via your gut microbiome creating short-chain fatty acids (SFAs) from it. It might also have some resistant starch if not fully cooked, which people on the potato diet might do occasionally by mistake.
Inulin (maybe)
Although I could only find one paper that showed this, potatoes might have inulin. I don't know if the Inulin is destroyed when you cook the potato although. Inulin is known to increase your GLP-1 creation.
Potatoes might reduce gut dysfunction & inflammation
I have a hypothesis that diets that reduce gut dysfunction often also make weight loss easier. I guess one reason why carnivore & keto diets might work well for many is it's the first time their gut has a break from the FODMAP category of foods, which gives their gut a general break if they have issues with them or a low-grade SIBO issue. Many people in the population have low-grade gut dysfunction that doesn't register as severe enough to treat. A majority potato diet might similarly give people's gut a break for once, or aggravate it.
Potatoes by having almost no fat, are basically 'seed oil' or PUFA free
Which is a currently popular theory as to why the obesity rates have increased significantly over the decades.
Potatoes might induce slower gastric transit times
which is associated with weight loss and GLP-1 medications. I've noticed slower gastric transit time myself.
Potatoes induce an aversion to sweet things for a few hours in me
When I'm eating potatoes, and a few hours after eating potatoes, eating anything sweet is 'too sweet' for me. This includes artificial sweeteners such as 25cal energy drinks, 5cal sugary sauces, and 60cal kombucha. If I wake up and drink an energy drink and don't eat potatoes, I'm ok. If I eat potatoes with sugary sauces, it quickly stops tasting good, and trying to drink kombucha an hour or two after eating potatoes is way too sugary.
Aversions to sweets is a super interesting thread to pull on, what is causing it? It feels like something that would also reduce weight.
Individual metabolic variation
Some people due to their genetics, unique body state, and microbiome tend to work better with one kind of micronutrient vs. another. Potato starch might work very well for people where starch is their favored metabolic pathway.
I used Genefood recently and found out I'm a 'villager', which means a majority starch diet is what works best for me according to my genetics. I also have a lower resting heart rate by 10bpm and better mental energy when on this diet. I also noticed similar effects when I tried the high starch emergence diet but did not lose weight on that one. It didn't have as much of an appetite reduction effect as the potato diet.
For others, especially for people the potato diet doesn't work for, might work best with fat and a ketogenic diet state.
tried the potato diet and it failed for him. He created a high-fat keto diet and it's the only thing that has worked well for him so far.Probably not the glycemic index
Potatoes have a variable glycemic index depending on the method of prep, and the prep method doesn't seem to change the weight loss effects. It tends to lean fairly high. I can't find anybody who did the diet while wearing a CGM, so I'm curious if it has the same expected glucose-spiking results that you would think from its relatively high glycemic index or if it acts somewhat differently.
When I checked my blood glucose today about 30m to 1h after eating potatoes, it was at 130mg/dl. After exercise and not eating for the entire day several days ago, it was at 89mg/dl, and I wasn't in ketosis at 0.3mmol. I might get a CGM soon to see how this diet affects me.
Why isn't there a potato chip diet?
Why are oily potato chips obesogenic? My guess is the fat probably interacts with the appetite-suppressant substances inside potatoes to neutralize them somewhat. Potato chips are also 2/3rds fat in calories (10g fat vs 14g carb).
It's also been shown that fat+carb combo foods are not typical outside of fall with nuts in the natural environment. Because of its uniqueness, it has been shown to induce overeating in mammals. Humanity has also discovered this and most of our desserts are created in this way too. The added salt also increases overeating.
Potato chips also exclusively use vegetable oils, or PUFAs, which might cause major issues when it's the majority of your calories.
All of these factors probably counteract the potato effect by a strong degree, which is why we probably don't see it happen in the wild.
For people who lose weight with a saturated fat + potato diet, a non-pufa potato chip such as masa chips might work if made with potatoes vs. corn at an affordable price.
Why does half-tato work for some?
My guess is you need enough potato inside a person to start inducing its appetite-suppressant effects. You need a substantial bolus of potato to induce GLP-1 creation in the gut while it's being digested. Not enough potato, not enough effects. With enough individual variation in sensitivity, you reduce the statistical likelihood that a reduced potato diet will still work when you go half-tato or tato-by-default.
Other foods introduced in a half-tato diet in a person might induce opposite effects and overwhelm or neutralize the potato effect, as shown by my potato chip hypothesis. Individual variation also probably makes these variable extras cancel out the potato effect or accelerate it even further. One person quadrupled their weight loss by adding a pure chocolate + milk drink for example.
For myself, I've naturally 'cheated' a few times when I ran out of potatoes, mostly with bread or frozen fruits, especially blueberries. If I ate enough bread during a night, it seemed to cancel the potato effect. But if I ate a moderate amount, such as 4 slices, it seemed to have no effect even though my appetite was less suppressed with bread. Eating blueberries also seems to have no negative effects.
I probably could accelerate this diet further by experimenting with stearic fatty acids and pure chocolate, but I'm already losing 0.9 lbs per day on most days, and going any faster will probably up my probability of lean mass loss and loose skin. I plan to get a DEXA scan soon to see the effects so far.
Besides nuts, a fat+carbs combo in nature is milk. Very low PUFA vs. nuts typically being very high, but still - and another suspicious diet food almost everybody will tell you to avoid when trying to lose weight.