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Dear Mark: Wheat Germ Agglutinin and Leptin, Early Allergen Introduction, Fasted Training, Green Bananas, and Sunchokes

For today’s edition of Dear Mark [7], we’ve got a five-parter. First, I discuss wheat germ agglutinin’s potential interaction with the leptin receptor. Next, I explore the prospect of introducing gluten [8] and peanuts (among other potential allergens) to youngsters as a way to prevent allergies from developing. I also discuss whether fasted workouts [9] are a sound strategy to boost fat burning, if any good non-nightshade sources of resistant starch [10] exist, and the nutritional benefits of sunchokes.

Let’s go:

Dear Mark,

This is one part question preceded by a brief story.

I am a science graduate student, and a couple years ago, I went to a seminar on leptin receptors in the brain. More specifically, the woman presenting had been trying to better understand projections of leptin receptors and leptin neurons beyond the arcuate nucleus of the hypothalamus. She had been using fluorescent wheat germ agglutinin (WGA) to figure out where the receptors are because WGA binds to leptin receptors. The thing that makes WGA so useful is that it sits on the leptin receptor for a really long time, though it doesn’t elicit the same downstream signaling effects as leptin. I was blown away, not by the intended presentation but by the clear depiction of WGA as a contributor to leptin resistance and other metabolic issues. I mean, the stuff crosses the blood brain barrier! (Also, leptin receptors exist beyond the arcuate nucleus).

Naturally, I waited for the research to come out about this. It never did. Maybe the leptin-resistance boat sailed a while ago and people don’t care as much. I guess my question is this: Why is the science community, of which I am a part, failing to make these connections? Why are we failing to get this critical information out there? What can we do to ask better questions?


Actually, a few people have noticed the WGA-leptin receptor connection. I wrote about it a few years back in my leptin post [11]. Staffan Lindeberg, author of the Kitava study and noted ancestral health researcher, wondered the same thing [12] in his paper discussing the differences between agrarian and non-agrarian (hunter-gatherer) diets. According to that paper, studies were in the works to examine whether dietary lectin interaction with leptin receptors occurred in vivo, but I haven’t heard much beyond that. Other studies [13] do what the presenter at your seminar did, though.

It’s a great observation. I find myself doing the same thing when reading studies. Rather than focus on the stated intentions of the researchers in a given study, I’ll often be looking at the compound they use to reliably induce a disease state.

Take the diets they use to fatten up rodents. These are diets that are used whenever a scientist wants to study obesity – because they so reliably make rats and mice incredibly overweight. They call them high-fat diets [14], but anyone who knows much about fat knows that “fat” doesn’t tell us a whole lot. Fats are bioactive compounds with very different health effects depending on their level of saturation [15], chain length, and arrangement of the atoms along the chain. Both beef tallow [16] and soybean oil will stain your clothes and prevent food from sticking to the pan – like all other fats – but the effects upon ingestion are very different.

The two most popular obesity-inducing “high-fat” diets use industrial lard as the primary fat. Lard. We love lard, right? It’s a traditional low-PUFA, low-omega-6 [17] specifically animal-derived cooking fat. Except that industrial lard is no longer low in PUFAs because of the industrial diets used to feed the pigs. According to the manufacturers of the high-fat rodent diets themselves (PDF [18]), the lard used is about 22-26% linoleic acid (compared to sub-10% in more traditional lard). Since dietary omega-6 is adipogenic [19], meaning it promotes the creation of new fat cells, we can see how a high-fat diet that’s actually a high-linoleic acid diet could be fattening. That’s never mentioned in the studies, though. Researchers are only interested in the effects of getting and being obese, not what’s causing the obesity. They take for granted that a “high-fat diet [20]” causes obesity, because, well, that’s “settled science.”

Excellent sleuthing.

For a long time it was thought that one should avoid giving toddlers and children common allergens, such as peanuts, shellfish, dairy. Recently, pediatricians have changed their thinking and now say it is important to expose children to such foods as it helps them to build antibodies early in life and may diminish the risk of having an allergy later in life. My daughter is 11 months old and I have not fed her any peanuts or gluten, as we follow a paleo diet. I am not keen on giving her peanuts or gluten as I know they can be very irritating to the gut, but I also want to avoid any future allergies and so a part of me feels like a bit of exposure may be good for her. What do you think??


I think there’s something to it. Look, a hallmark of the Primal Blueprint [21] and other ancestral health eating plans is avoidance of wheat [22]. The fact remains, though, that your kids are going to come of age in a food environment where wheat and peanuts [23] are extremely prominent. There will be birthday parties with cake, sleepovers with peanut butter sandwiches, pizza parties. It’s everywhere. They may want to include those foods in their diet (regardless of, or perhaps because of, your attempts to prevent it) when they get old enough to control what they eat, and you should prepare them.

I’m not saying you should give them cream of wheat every morning or peanut butter sandwiches for lunch. But a little bit probably won’t hurt, and it may help prime their immune system so that any future choices are theirs and theirs alone.

Here’s how I’d handle it, if you’re going to do it:

Unfortunately, optimal timing of gluten introduction is unknown. We do know that 3-4 months is way too early (PDF [28]) and increases the risk of celiac. Some research claims that 4-6 months is the sweet spot, while noted gluten researcher Alessio Fasano has preliminary research [29] suggesting that delaying gluten exposure to 1 year can delay the onset of celiac disease in vulnerable populations. It sounds like 6 months and onward might be the best bet, but I can’t say that with total confidence. Luckily, more research from Fasano’s group should be coming later this year.

Again, I may be inviting lightning bolts from the paleo gods, but so be it. We do what’s best for our kids, right?

Dear Mark,

I’m trying to do my workouts on an empty stomach to make my body tap into my fat reserves. However, I often find myself lacking the energy to do a workout on a completely empty stomach, so I often have a black coffee with a teaspoon of coconut oil before. Now I was wondering though whether that negates the whole idea of making my body tap into its fat stores because it just uses the coconut oil instead?

Thanks in advance!


The real beauty of a good workout is not the mechanical consumption of calories that occurs during the workout itself. It’s that your ability to oxidize fat for fuel is upregulated and enhanced [30]. Your mitochondria become more adept at burning fuel [31], your muscles become more sensitive to the effect of insulin (thus requiring less of it), and the food you do consume gets partitioned as lean, rather than fat, mass. And, with regular workouts, that ability to oxidize body fat [32] and preferentially store energy substrates stays elevated (or rather normalized).

The problem with insisting on fasted training is exactly what you’re experiencing – lack of energy is common. I recall one of our worker bees here who got really into fasted training [33] and ended up feeling like working out with food in his stomach was a waste. Problem was he often ran out of energy – just like you – for workouts and his workout consistency and progress dropped off a cliff because he didn’t want to train with food in him. It wasn’t until he divested himself from the “fed training = wasted training” mindset that he was able to resume progress and get stronger and fitter.

It’s a tricky balance, because workouts on an empty stomach are effective in their own way, and fat oxidation is generally favored over glycogen oxidation since there’s not as much of the latter to go around, but you have to do the workouts. If you don’t have the energy to do them, you don’t get the benefit. Ironically, I bet if you made sure to fuel up before your workouts for the next month or so, your fat-burning machinery would be humming [34] along enough that you could then do workouts in a fasted state without feeling depleted. Even though I don’t make it a point to work out in a fasted state, I can do it without much of an issue if I have to because my fat burning ability is optimized.

In my experience, the best activities to do in a fasted state are really low level movement type stuff, like walking, hiking, cycling, maybe some yoga or real short, real simple body weight exercise routines. The folks who try to consistently lift heavy [35], run intervals [36], or go for distance [37] on an empty stomach every single workout tend to crash and burn in the long run, at least from what I’ve seen and heard (in emails and messages from readers). There are outliers, vocal ones, but you might not be one of them.

In short, eat whatever you have to eat to initiate and complete the workout! Try the fasted training again later when you’ve got more of your ducks in a row.

Hi Mark,

I have been reading all about resistant starch and am convinced of its benefits. However when I tried the raw potato starch I immediately had a flare up of my autoimmune skin condition (presumably from the nightshades). Is there any other source of resistant starch that you can recommend for a reactive hypoglycemic who doesn’t tolerate carbs such as white rice? We don’t get plantains here in Australia. Do you know whether tapioca flour is a good source of resistant starch, and is it likely to send my blood sugar souring? Should I deviate from the primal recommendations and add some properly prepared beans or lentils to my diet, or rather forget the whole resistant starch thing? Any thoughts would be greatly appreciated.



The safest bet for you would be unripe bananas. You can get those, right? A green banana can contain as much as 34 grams of resistant starch (PDF [38]). You’ll know a banana is high in RS when you bite into it: it’s not very sweet and has a gritty, sandpaper-esque texture that dries your mouth out. It’s not delicious by any means, but it’s definitely edible and it blends well in smoothies. Plus, it’s real, whole food, full of vitamins and minerals and phytonutrients [39].

Properly prepared beans and lentils are another option, yes, but you may find the antinutrients they contain also give you autoimmune flare-ups. So be prepared for that. They’re also much higher in digestible carbs, which could be a problem depending on your normal carb intake [40] and activity level (although the higher RS content can ameliorate that to some extent by improving insulin sensitivity and lowering the blood glucose response).

The good news is that eating resistant starch and other forms of prebiotics [41] (see next question) may eventually improve your gut health to the point where nightshades [42] no longer give you issues. It’s just a guess, but lots of food sensitivities are related to the health of our gut flora – which, as you may know, comprise most of our immune system. Might be an interesting experiment [43] to try the potato starch (and other nightshades) after you’ve settled into a nice routine with prebiotics to see if your tolerance changes.

Potatoes bad, sweet potatoes good. Check.

What about things like parsnips, sunchokes, jicama? There are so many yummy veggies that don’t make it onto either the avoid or gorge list, usually I just go with moderation. But in the case of sunchokes, they are SO easy to grow in my neck of the woods, and the flowers so pretty, I’ve kinda let them take over the garden. Can I eat them with reckless abandon? I’d love if you could dig up (har har) some info on them (and whatever other less common edible roots too).


These foods are all good. Jicama [44] is delicious with some lime, salt and chile powder. Parsnips [45] make good fries and mashes. Sunchokes are a different beast entirely.

Tread lightly, Julia. Tread very lightly. Sunchokes, also known as jerusalem artichokes, are incredibly rich with inulin [46], one of the premier prebiotics and FODMAPs [47]. They have the potential to bolster your gut flora [48], increase butyrate production [49], and improve your digestive health [50]. They also have the near-certain potential to increase the breadth, depth, and hilarity of your farts [51].

That’s right. If you insist on availing yourself of all the sunchokes your garden can produce, expect the generation of reckless amounts of gas that will then abandon your body of their own volition. “Reckless abandon” indeed.

Jicama is also high in inulin, but less so than the sunchoke. I’ve noticed a distinct difference in my gut’s response to jicama – which I can eat quite freely – and the sunchoke – with which I have to exercise restraint.

That’s it for this week, folks. Thanks for reading and be sure to keep sending in questions!