Why I Think the Paleo Diet Is Silly

Late­ly, many nutri­tion gurus have been pro­mot­ing what they call a “paleo” diet. The word “paleo” comes from Pale­olith­ic, which lit­er­al­ly means “ear­ly stone age.” They think that human beings ought to be eat­ing a diet like the diet that peo­ple ate dur­ing the ear­ly stone age. Per­son­al­ly, I think that the argu­ments in favor of the paleo diet are sil­ly, for sev­er­al rea­sons. I think that the appeal of the paleo diet is based on ado­les­cent male fan­tasies of being an unwashed, unshaven big game hunter who gets to spend time with a hot-look­ing maid­en in a fur or leather biki­ni. Real men don’t eat quiche. They eat bron­to­burg­ers:

Con­tin­ue read­ing “Why I Think the Paleo Diet Is Sil­ly”

Low-Fat, High-Carb Diets Reverse Insulin Resistance

Dr. George Lund­berg, the for­mer edi­tor-in-chief of JAMA, gra­cious­ly invit­ed me to coau­thor this edi­to­r­i­al on how starchy, low-fat diets reverse insulin resis­tance!

Con­tin­ue read­ing “Low-Fat, High-Carb Diets Reverse Insulin Resis­tance”

Humans Are Starch Eaters

Here’s an inter­est­ing talk by Nathaniel Dominy, PhD, an Asso­ciate Pro­fes­sor of Anthro­pol­o­gy at Dart­mouth Uni­ver­si­ty. He explains the cen­tral role of diet in the amaz­ing world­wide suc­cess of the human species. If you can’t find enough to eat, you can’t do any of the oth­er things that you would need to do to help you and your chil­dren sur­vive.

He makes sev­er­al impor­tant points. One is that human beings are behav­ioral­ly “plas­tic.” He uses the term “plas­tic” in the sci­en­tif­ic sense, mean­ing that some­thing can take any shape. Our behav­ior is “plas­tic” because it can eas­i­ly be reshaped. As he point­ed out, human beings can adapt to many dif­fer­ent cli­mates because we have learned to make and wear clothes. We can also learn to eat lots of dif­fer­ent foods.

One type of food that is avail­able every­where except the Artic is starchy foods. All of the ener­gy in our diet comes from sun­light, which green plants use to make glu­cose out of car­bon diox­ide and water. Plants then store a lot of this glu­cose in the form of starch, often in their roots or tubers and in their seeds. Unfor­tu­nate­ly, starch is hard to digest. To digest it, we use amy­lase, an enzyme that con­verts the starch back to glu­cose.

Dominy sus­pects that our ances­tors’ abil­i­ty to rec­og­nize and use tuber-form­ing plants opened up a food source unknown to oth­er pri­mates. “It’s kind of a gold mine. All you have to do is dig it up.

Dominy points out that, when com­pared with oth­er pri­mates, human beings have extra copies of the gene for the starch-digest­ing enzyme amy­lase. As a result, we have a lot more amy­lase in our sali­va than goril­las or chim­panzees do. Peo­ple from soci­eties that depend heav­i­ly on starchy diets have sev­er­al more extra copies of the amy­lase gene and there­fore pro­duce a lot more amy­lase in their sali­va. In oth­er words, they have become genet­i­cal­ly more effi­cient at digest­ing starch­es. This kind of change can be seen in genet­i­cal­ly relat­ed pop­u­la­tions that have been adapt­ing to dif­fer­ent diets for only a few thou­sand years.

Although humans can and do eat prac­ti­cal­ly any­thing (we are behav­ioral­ly plas­tic), that doesn’t mean that we are well adapt­ed to a meat-based diet. As he puts it, “Anatom­i­cal­ly, we’re not adapt­ed to meat at all…. We sim­ply don’t have the adap­ta­tions that you would need to chew meat effi­cient­ly. Any­one can look at the teeth of their dog or cat and see what your teeth should look like if you’re going to eat meat. Our teeth don’t match.” Dominy con­cludes, “The fun­da­men­tal com­po­nent of the human diet is a mix of plant foods, with a large amount of starch com­ing from tubers and seeds.”

In this con­text, I’d point out that the adap­ta­tions to a meaty diet go far beyond the shape of the teeth. Even though dogs often eat a fat­ty, meaty diet, they gen­er­al­ly don’t get high cho­les­terol or ath­er­o­scle­ro­sis unless they also have a thy­roid dis­or­der that upsets their cho­les­terol metab­o­lism. In con­trast, human beings that eat a fat­ty, meaty diet are much more sus­cep­ti­ble than dogs are to high cho­les­terol and ath­er­o­scle­ro­sis. That explains why ath­er­o­scle­ro­sis is the lead­ing cause of death in the Unit­ed States but prac­ti­cal­ly nonex­is­tent in soci­eties where peo­ple eat a low-fat, plant-based diet.

Why I Don’t Worry About Sugar

Most of the peo­ple I talk to about nutri­tion are con­vinced that car­bo­hy­drates are their ene­my. They think that “sug­ar spikes” cause dia­betes. (They have it back­wards. Sug­ar spikes are the result, not the cause of dia­betes!) Peo­ple seem to be par­tic­u­lar­ly wor­ried about the effects of a sug­ar called fruc­tose. Per­son­al­ly, I’m not wor­ried about car­bo­hy­drates, even fruc­tose, as long as it’s found in an unre­fined plant source. I even think that adding a spoon­ful of sug­ar or per­haps some maple syrup every now and then could help a lot of peo­ple stick to a healthy low-fat, plant-based diet.

Genet­i­cal­ly, human beings are almost iden­ti­cal to chim­panzees. Our DNA is almost exact­ly the same as theirs, which means that our body chem­istry is also almost exact­ly the same as theirs. Since chim­panzees, like many oth­er apes, are main­ly fruit-eaters (fru­gi­vores), it stands to rea­son that they prob­a­bly thrive on a diet that con­tains a lot of fruc­tose, which is a sug­ar that is com­mon in fruit. How­ev­er, the fruc­tose that wild chim­panzees eat is dilut­ed with water and fiber and pack­aged along with plen­ty of oth­er nutri­ents, along with antiox­i­dants and oth­er good things.

Yes, you can make your­self sick by eat­ing too much sug­ar. How­ev­er, it would be dif­fi­cult for most peo­ple to get that much sug­ar from eat­ing fruit! One study found that eat­ing way too much added sug­ar (at least 25% of total calo­ries!) is asso­ci­at­ed with only a rel­a­tive­ly small increase in the amount of fat (triglyc­erides) in the blood and a small decrease in the lev­el of HDL (“good”) cho­les­terol. Of course, if you are hav­ing a prob­lem with triglyc­erides, you should prob­a­bly cut way back on your con­sump­tion of table sug­ar and high-fruc­tose corn syrup.

Sug­ar does rot your teeth, at least if you don’t brush care­ful­ly after meals. As a result, chim­panzees are prone to den­tal caries (cav­i­ties), just as humans are. How­ev­er, wild chim­panzees don’t seem to be fat and dia­bet­ic and they don’t get heart dis­ease. So why should I imag­ine that I would get fat and dia­bet­ic and suf­fer from heart dis­ease if I ate a lot of fruit?

Eat­ing lots of sug­ar does not cause dia­betes. Instead, cow’s milk seems to be the cul­prit in caus­ing type 1 dia­betes. A diet that is high in fats and ani­mal pro­tein seems to be the under­ly­ing cause in type 2 dia­betes.

Eat­ing too many calo­ries from any kind of diet tends to make peo­ple gain weight. How­ev­er, you gain a lot more weight from extra calo­ries from a fat­ty diet than from extra calo­ries from a high-car­bo­hy­drate, low-fat diet. Con­vert­ing sug­ar to fat wastes calo­ries. That’s why it’s hard to fat­ten on carbs but easy to fat­ten on fats.

Of course, there are a few peo­ple with genet­ic dis­or­ders that make it hard for them to tol­er­ate fruc­tose. One of them is hered­i­tary fruc­tose intol­er­ance. Anoth­er is fruc­tose mal­ab­sorp­tion.

Hered­i­tary fruc­tose intol­er­ance is a poten­tial­ly fatal genet­ic dis­or­der that occurs in about 1 out of 20,000 peo­ple in Euro­pean coun­tries. The dis­or­der results from the lack of an enzyme called aldolase B. In peo­ple with this dis­or­der, eat­ing any­thing con­tain­ing fruc­tose, includ­ing sucrose (table sug­ar), sets off a series of com­pli­cat­ed meta­bol­ic prob­lems that can ulti­mate­ly cause liv­er dam­age. The only solu­tion is for these peo­ple to avoid any foods that con­tain sucrose or fruc­tose.

Fruc­tose mal­ab­sorp­tion is an unre­lat­ed prob­lem that is far more com­mon but much less seri­ous than hered­i­tary fruc­tose intol­er­ance. Fruc­tose mal­ab­sorp­tion results from the absence of fruc­tose trans­porters in the cells that line the small intes­tine. With­out fruc­tose trans­porters, the per­son can­not absorb fruc­tose from his or her food. Even peo­ple who have some fruc­tose trans­porters might be able to absorb only a lim­it­ed amount of fruc­tose. The remain­ing fruc­tose will then remain inside the intestines, where it will be fer­ment­ed by bac­te­ria. The result is syn­drome that looks a lot like lac­tose intol­er­ance: gas and diar­rhea. Fruc­tose mal­ab­sorp­tion is a com­mon but often unde­tect­ed cause of recur­rent abdom­i­nal pain in chil­dren.

For­tu­nate­ly, I don’t have hered­i­tary fruc­tose intol­er­ance or fruc­tose mal­ab­sorp­tion. This means that I can eat as much fruit as I like!

Note: For a clear expla­na­tion of how the body han­dles sug­ar, see my book Thin Dia­betes, Fat Dia­betes: Pre­vent Type 1, Cure Type 2.

Behind Barbed Wire_Print