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Is Saccharide Fattening?

Buckle your topographic point belts, ladies in addition to gentlemen-- we're going on a long ride through the scientific literature on refined saccharify in addition to torso fatness.  Some of the evidence volition live on surprising in addition to challenging for many of you, as it was for me, but ultimately it paints a coherent in addition to actionable picture.

Introduction: What Exactly are Sugar in addition to Starch?

In this post, I'll live on using the give-and-take 'sugar' to refer to iii things: 1) sucrose, or tabular array sugar, 2) high-fructose corn syrup (HFCS), in addition to 3) fruit in addition to beloved sugars.  Sucrose is composed of 1 molecule of glucose in addition to 1 molecule of fructose, linked together, in addition to it is thus 50:50 glucose:fructose.  When yous eat sucrose, this bond is chop-chop broken, releasing gratuitous glucose in addition to fructose, which are in addition to so absorbed.  HFCS is a mixture of gratuitous glucose in addition to fructose that comes inwards ii mutual varieties: 42:55  in addition to 53:42 glucose:fructose.  The old is most often used inwards soft drinks, piece the latter is most often used inwards baked goods.  Since sucrose in addition to HFCS are both refined sugars composed of roughly one-half glucose, one-half fructose, 1 would await them to remove hold similar effects on the body, in addition to controlled experiments overall remove hold confirmed this.  Fruit refined saccharify is a mixture of sucrose, gratuitous glucose in addition to gratuitous fructose.  Honey is composed of roughly one-half gratuitous fructose, in addition to one-half gratuitous glucose, but the ratio depends on the type of flowers visited past times the bees.

Glucose is the shape of saccharide that predominates inwards the blood, in addition to along alongside obese acids, it's 1 of the ii primary fuel sources for the body.  Starch is composed of long chains of glucose that are chop-chop broken upwards during digestion.  Because of this, dietary starch is similar to dietary glucose inwards the agency it affects the torso afterward ingestion. 

Primate in addition to Human Evolutionary History alongside Sugar

The earliest primates living to a greater extent than than lx 1000000 years agone probable subsisted on fruit, leaves in addition to insects, as most primates do today (Richard Klein. The Human Career. 2009).  Chimpanzees in addition to bonobos, our closest living primate relatives ( 6 1000000 years of divergence), are mostly frugivorous, pregnant they're fruit eaters that obtain much of their release energy from fruit sugars.  For what it's worth (perhaps non much), these primates are both extremely lean inwards the wild.  It's probable that our terminal mutual ancestor alongside them relied heavily on fruit.

Humans belike began to diverge from our ancestral primate dietary patterns about 2.6 1000000 years agone when nosotros developed rock tools.  Archaeologists retrieve this is when pre-humans began hunting/scavenging animate beingness foods to a greater extent than oftentimes in addition to relying to a greater extent than on animate beingness sources of nutrition (Richard Klein. The Human Career. 2009).  Some fourth dimension over the ensuing ii 1000000 years or so, nosotros began using burn regularly in addition to eating to a greater extent than starch foods, also presumably at the expense of leaves, fruit in addition to insects.

However, our ancestors never abandoned their fruit-eating ways, in addition to modern hunter-gatherers hold to eat fruit in addition to beloved when available.  In equatorial in addition to many temperate regions, fruit in addition to beloved together are a major root of calories during much of the year, in addition to thus the diet contains a important amount of sugar.  For example, the Hadza hunter-gatherers of Tanzania rely heavily on fruit in addition to beloved (1).  !Kung hunter-gatherers of the Kalahari desert also eat a substantial amount of fruit in addition to sometimes beloved (Richard Lee. The !Kung San. 1985).  Both groups are characteristically lean.  These cultures presumably eat inwards a agency that resembles the diet of our ain human ancestors.

There are also many examples of non-industrial horticultural in addition to agricultural groups that eat fruit regularly.  For example, according to the piece of work of Dr. Staffan Lindeberg, residents of the Melanesian isle of Kitavans obtain 50 g of saccharide per twenty-four hours from fruit, most of which would presumably live on refined saccharify (3).  This is virtually one-half the amount of refined saccharify Americans eat today (discussed below).  Dr. Lindeberg's inquiry showed that Kitavans are quite lean, in addition to remove hold an undetectable incidence of pump attacks, stroke in addition to diabetes.  Their fasting insulin levels are depression past times Western standards. 

It is hard to escape the decision that our ancestors remove hold been consuming sugar, inwards the shape of whole fruit, continuously for the terminal lx 1000000 years. 

Recent History of Sugar Consumption inwards the US of America in addition to Correlation alongside the Obesity Epidemic

Sugar intake inwards the US of America has increased greatly over the terminal 200 years, mostly due to an increment inwards added refined sugars.  In 1822, the average American consumed an estimated 6.3 pounds of added refined saccharify per year, piece inwards 2004, consumption had increased to 101 pounds per year, a 16-fold increase.

This sounds similar it could seriously implicate refined saccharify inwards the obesity epidemic, but a closer inspection of the numbers complicates matters. 

The CDC's NHANES surveys documented the outset of the US of America "obesity epidemic" betwixt the 1978 in addition to 1991 survey periods, as good as a continued increment inwards obesity rates throughout the 2000s.  Between 1978 in addition to 2004, the prevalence of obesity inwards US of America adults increased from fifteen to 33 percentage (NHANES).  Over that same fourth dimension period, added refined saccharify intake increased from 86 to 101 pounds per year, a 17 percentage increase.  On this basis, it could potentially live on a cistron inwards the obesity epidemic.  However, in that location are clearly other factors involved, since a 17 percentage increment inwards refined saccharify consumption cannot reasonably concern human relationship for the total 120 percentage increment inwards obesity prevalence over this fourth dimension period. 

Observational Studies inwards Humans

Observational diet studies endeavor to mensurate what people are eating inwards their day-to-day lives, in addition to correlate that alongside other measures such as weight or health.  There remove hold been a issue of observational studies on refined saccharify consumption in addition to torso fatness, in addition to they remove hold yielded surprising but relatively consistent results.  I'll allow the authors of a review newspaper summarize (4):
In all cases inwards which the association is significant, in that location is an inverse relation betwixt sucrose or saccharide intake in addition to [body volume index]...
We give away no argue at introduce to associate high consumption of refined saccharify alongside obesity.
What the authors are referring to is that 4 out of the vi studies they reviewed constitute that people who eat the most refined saccharify are the leanest, in addition to the remaining ii studies constitute no association.  The authors constitute an inverse human relationship betwixt refined saccharify intake in addition to dietary obese intake, in addition to speculate that the argue people who study higher refined saccharify intake are leaner is because they eat less fat. 

This decision must live on viewed alongside caution, because the method that's typically used to assess nutrient intake inwards these studies, the nutrient frequency questionnaire, is non real practiced at measure the intake of sugar-sweetened foods in addition to other foods that people stance as unhealthy (5).  That's belike because people wishfully under-report them.  According to a newspaper evaluating the nutrient frequency questionnaire:
These findings for specific foods propose that participants over-reported consumption of foods often considered desirable or healthy, such as fruit in addition to vegetables, in addition to underestimated foods considered less desirable. 
The grade of under-reporting is belike non evenly distributed across the populations they're studying.  This is a work that often plagues observational studies but is typically ignored.

What virtually sugar-sweetened beverages (SSBs) such as soda?  In contrast to total refined saccharify intake, higher intake of SSBs is to a greater extent than often than non associated alongside higher torso fatness (6, 7).

In recent years, researchers remove hold gotten to a greater extent than sophisticated virtually measure obese mass, in addition to at nowadays they often aspect at torso obese distribution rather than but total obese mass.  H5N1 recent study constitute that fructose intake, mostly from sweetened beverages in addition to food, was non associated alongside total torso fatness inwards US of America adolescents, but it was associated alongside higher visceral (belly) obese volume specifically (8).  It was also associated alongside insulin resistance, markers of inflammation in addition to higher blood pressure-- all components of the metabolic syndrome.  As nosotros volition see, this finding is quite representative of the inquiry on refined saccharify as a whole.

Overall, the observational evidence suggests that refined saccharify inwards the shape of SSBs is associated alongside elevated torso fatness, but total refined saccharify intake is not.  This is our foremost clue that this story may live on to a greater extent than complicated than "sugar makes yous fat".

Controlled Studies inwards Animals

There remove hold been literally hundreds of animate beingness studies on refined saccharify in addition to torso weight/fat gain, most of which were conducted inwards rodents.  Sugar, when compared to starch inwards the context of a pelleted diet, tin laissez passer the axe promote torso obese gain inwards rodents inwards some contexts (9, 10, 11), but inwards some cases refined saccharify genuinely leads to similar or fifty-fifty less less obese deposition than starch (12, 13, 14, 15).  Diets high inwards refined saccharify in addition to obese together tend to live on the most fattening of all (16, 17).  The most usually used fattening rodent diet, Research Diets D12492 (and related diets), is 34 percentage obese in addition to nine percentage refined saccharify past times weight (60 in addition to 7% past times calories, 18).  This recipe was created past times trial in addition to error, in addition to it's real effective at chop-chop producing obesity inwards rodents-- to a greater extent than effective than whatever high-sugar low-fat diet.  We'll come upwards dorsum to why the composition of D12492 is an obesity "sweet spot" inwards a moment. 

There's some other agency to fatten rodents using sugar-- add together it to the drinking water.  Offering rodents sweetened liquids consistently causes torso obese accumulation (19).  

How tin laissez passer the axe nosotros explicate the discrepancy betwixt studies that reported that refined saccharify is fattening, in addition to those that reported that it isn't, or fifty-fifty that it's slimming?  One thing I've noticed is that the pelleted diets that are the lowest or highest inwards refined saccharify (e.g. 0% or 64 -73%) tend to live on the least fattening, piece diets that are inwards betwixt (9 to 54%) tend to live on the most fattening.  This is non what nosotros would await if refined saccharify were inherently fattening, inwards which instance to a greater extent than refined saccharify should atomic number 82 to to a greater extent than torso obese accumulation.  There's a parsimonious explanation for these observations, which is summarized inwards this graph showing the refined saccharify gustatory modality preferences of rats (20).  Rats were offered a choice betwixt patently distilled H2O in addition to refined saccharify water, in addition to this was repeated alongside solutions containing dissimilar concentrations of sucrose:

Rats similar sweetness fluids, in addition to the to a greater extent than refined saccharify yous add, the to a greater extent than they imbibe relative to patently water... upwards to a point.  Beyond 27 percentage sucrose (w/v), their refined saccharify H2O intake plummets, in addition to they become dorsum to preferring patently H2O past times 37 percent.  There's a uncomplicated argue for this: they don't similar the taste.  Rats in addition to humans alike remove hold a palatability "sweet spot" for sugar, in addition to exceeding it makes nutrient unpalatable (commercial sweetened beverages are all inside the human sweetness spot).  Sugar tastes good, but imagine yourself getting seventy percentage of your calories from patently refined saccharify cubes.  You would larn sick of it almost immediately.  Together, this suggests that refined saccharify may travail torso obese accumulation inwards rodents inwards large component subdivision because it tastes practiced in addition to it's rewarding, rather than because of some inherent metabolic lawsuit of sugar. 

To farther explore this point, let's accept a aspect at studies that compared refined glucose in addition to fructose feeding.  Glucose, as we've discussed, is metabolically real similar to starch afterward consumption, because starch breaks downwards into glucose chop-chop inwards the gut.  Sugar (sucrose or HFCS) is roughly 50:50 glucose in addition to fructose.  So whatever inherent metabolic effects of refined saccharify that are dissimilar from starch would live on expected to come upwards from the fructose portion.  Directly comparison dietary glucose to fructose allows us to some command for the sweetness (flavor) of the diets piece identifying whatever unique fattening effects of fructose.  This is the limitation of studies that compared refined saccharify to starch: palatability/reward differed betwixt conditions, so there's no agency to know for sure which effects are due to palatability/reward, in addition to which are due to inherent metabolic properties of sugar. 

The studies that compared glucose to fructose are surprisingly consistent alongside 1 some other inwards rodents, dogs, in addition to (discussed below) humans.  When diets high inwards glucose are compared head-to-head alongside diets high inwards fructose (and sometimes sucrose), the fructose diet increases circulating insulin, causes insulin resistance inwards the liver, but total torso fatness remains similar betwixt the glucose in addition to fructose groups inwards almost every instance (22, 23, 24, 25, 26, 27, 28).  This is also truthful if the sugars are administered side-by-side inwards drinking H2O (28a).  There is no difference inwards the effects of glucose, fructose or sucrose on total torso fatness inwards animate beingness models, suggesting that refined saccharify belike does non remove hold an inherently fattening lawsuit that is independent of its calorie content in addition to flavor. 

Now, let's larn dorsum to that extremely fattening pelleted diet, Research Diets D12492.  H5N1 primal argue why it's so fattening to rodents is belike because it combines 1) a preferred concentration of fat, 2) a preferred concentration of sugar, 3) a high release energy density, 4) a soft in addition to preferred texture, in addition to 5) constant accessibility.  Both obese in addition to refined saccharify are inwards the palatability/reward sweetness spot, neither also high nor also low, in addition to rodents are crazy virtually the gustatory modality of it.  It's correct nether their noses all day, in addition to they remove hold nada improve to do than eat it*. 

As a whole, the animate beingness inquiry suggests that refined saccharify in addition to fructose are belike non inherently fattening, but that they tin laissez passer the axe live on fattening when they are used to increment the palatability, vantage value in addition to release energy density of foods in addition to beverages.

Controlled Studies inwards Humans

Fortunately for us, in that location are many controlled human studies investigating the effects of refined saccharify consumption on torso fatness, in addition to in that location is to a greater extent than than plenty data to come upwards to a reasonable conclusion.  Let's start alongside the most extreme instance I have: a 1971 newspaper titled "Physiological Effects of a Mainly Fruit Diet inwards Man" (29).  Subjects ate nada but fruit (82% of kcal) in addition to nuts (18% of kcal) for vi months.  The diets were 52-65 percentage saccharide (mostly from fruit sugar), 37-45 percentage obese (nuts in addition to avocado), in addition to 5.6-8 percentage protein.  These fascinating quotes amount upwards their findings:
H5N1 considerable issue of the normal subjects claimed that their physical status improved piece they were on the diet.  Some were convinced that their stamina increased in addition to that their might to undertake strenuous physical tasks in addition to to compete inwards sport improved.

From these figures it is clear that most subjects lost weight initially... After the initial loss, the weights of the subjects inwards grouping B leveled off at figures which corresponded to a greater extent than or less alongside the calculated theoretical normal weights...

H5N1 few of these who were mildly overweight, constitute this diet an first-class incentive to reduce, in addition to consequently showed a greater decrease inwards weight than the others.  An interesting aspect of the diet was the vogue for the weights to bird off to a greater extent than or less at the 'theoretically ideal' weight for the subject.  This may partly explicate why some lost to a greater extent than weight than others.
These people obtained the bulk of their calories from unrefined refined saccharify for 6 months, yet their torso weights approached the 'theoretical ideal', alongside lean subjects remaining lean in addition to overweight subjects losing weight.  This finding is hard to reconcile alongside the thought that refined saccharify is inherently fattening.  It is also an first-class illustration of a 'simple' (reduced reward) whole food-based diet normalizing torso obese volume inwards humans.  I retrieve this diet isn't nourishing plenty to live on sustainable inwards the long term, but it surely emphasizes the do goodness of whole, uncomplicated nutrient on torso obese mass, regardless of refined saccharify content. 

H5N1 2nd instance of weight loss on a high refined saccharify diet is the "bland liquid diet" study I've referenced on this spider web log several times.  Volunteers were restricted to a bland liquid formula that was high inwards sugar, but were non asked to confine calories.  While lean subjects maintained a normal calorie intake in addition to torso weight, obese subjects experienced a greatly reduced appetite in addition to chop-chop lost weight, alongside 1 human losing 200 lbs over 255 days (30).  This 1 time once again shows that weight loss is possible on a high-sugar diet if it's lower inwards palatability in addition to vantage value.

H5N1 3rd real instructive study was published inwards 2002 (31).  Investigators recruited overweight volunteers alongside the metabolic syndrome (people who should live on refined saccharify sensitive if anyone is) in addition to assigned them to 1 of iii diets for 6 months:
  1. Replacing 1/4 of daily obese intake alongside 'simple carbohydrates' (sugared foods)
  2. Replacing 1/4 of daily obese intake alongside 'complex carbohydrates' (both refined in addition to unrefined starch foods)
  3. A command diet inwards which nada was deliberately changed
None of the diets were calorie restricted.  Over the class of 6 months, grouping #2 lost nine pounds (4.25 kg), but in that location were no important changes inwards grouping #1 or #3 (although grouping #1 did lose 0.6 lbs).  This suggests that sugared in addition to obese foods are as fattening inwards the context of a typical diet, since substituting 1 for the other had no lawsuit on torso weight.  However, replacing obese foods alongside starchy foods produced weight loss, suggesting that the most usually eaten sugared in addition to obese foods are fattening relative to starch foods.  This study was unique because it replaced 1 thing alongside some other rather than but restricting or adding foods.

There are several studies showing that high-sugar diets do non impair weight loss inwards the context of a low-calorie diet (32, 33), 1 time once again confirming the primacy of calorie intake inwards weight loss.

Now let's examine studies that compared glucose to fructose feeding inwards humans, which would topographic point whatever unique fattening in addition to metabolic effects of fructose, in addition to past times inference, sugar.  Perhaps the most interesting study was conducted past times Dr. Peter J. Havel's grouping inwards 2009 (34).  They had volunteers obtain 25 percentage of their release energy needs from beverages sweetened alongside either glucose or fructose, for 10 weeks, without controlling total calorie intake.  They used precise measures of torso composition in addition to distribution earlier in addition to afterward the intervention.  Here's how total torso obese volume changed inwards each group:

In perfect understanding alongside the animate beingness studies inwards rodents in addition to dogs, total torso fatness increased the same amount inwards both groups provided alongside refined glucose- or fructose- sweetened beverages.  Also reminiscent of the animate beingness studies, the fructose grouping saw a rapid increment inwards visceral obese specifically, an increment inwards fasting insulin in addition to insulin resistance, in addition to an increment inwards blood pressure.  Thus although the refined fructose strongly promoted elements of the metabolic syndrome, it did non remove hold whatever special might to increment total obese volume beyond what occurred but past times adding a sweetened potable to the diet.  It's worth noting that these volunteers were receiving real large quantities of refined fructose, which it would live on hard to obtain via a normal diet.

This outcome is consistent alongside a issue of other fructose feeding studies inwards humans, reviewed inwards a build novel newspaper inwards the Annals of Internal Medicine (35).  The investigators reviewed 41 human fructose feeding trials.  They concluded that fructose is non fattening when substituted for other saccharide inwards the diet, but it tin laissez passer the axe live on fattening if consumed inwards add-on to the typical diet.  This fattening lawsuit is equivalent to what 1 would await based on the increment inwards calorie consumption inwards these trials. 

OK, so high-sugar diets don't necessarily hit torso obese accumulation inwards humans, in addition to they tin laissez passer the axe fifty-fifty allow torso obese loss nether some circumstances, but are in that location situations where refined saccharify tin laissez passer the axe travail obese accumulation?  The respond is an emphatic yes.

The most convincing studies inwards this regard were aimed at reducing the consumption of SSBs such as soda.  These to a greater extent than often than non demonstrate that replacing refined saccharify alongside starch or non-caloric sweeteners leads to reduced calorie intake in addition to weight loss (36).  In 1 recent study, investigators recruited obese in addition to overweight volunteers, in addition to had them supervene upon the SSBs that they were already consuming alongside either diet beverages or H2O (37).  Over a 6 calendar month period, both groups lost virtually five pounds, much of it from their abdominal region, suggesting that the SSBs were 1 of the reasons they carried excess obese to start with. 

The controlled human studies 1 time once again propose that refined saccharify in addition to fructose are non inherently fattening, but that refined refined saccharify tin laissez passer the axe travail torso obese accumulation when it's used to increment the palatability, vantage value in addition to release energy density of nutrient in addition to beverages.  However, excessive consumption of refined refined saccharify tin laissez passer the axe promote elements of the metabolic syndrome, in addition to this is due specifically to its fructose content. 


Here are the take-home points from this post:
  1. Sugar, including fructose, is non inherently fattening relative to other calorie sources, in addition to unrefined refined saccharify is compatible alongside obese loss inwards the context of uncomplicated whole nutrient diets.
  2. Sugar tin laissez passer the axe live on fattening inwards sure contexts, specifically if it is added to foods in addition to beverages to increment their palatability, vantage value in addition to release energy density.
  3. Sugar-sweetened beverages are belike 1 of the most fattening elements of the modern diet.
  4. Fruit is non fattening, in addition to it may genuinely live on slimming.
  5. In excess, refined refined saccharify tin laissez passer the axe travail torso obese to redistribute from the subcutaneous depot (under the skin, where yous desire it) to the visceral depots in addition to the liver (where yous don't desire it). It tin laissez passer the axe also travail insulin resistance inwards the liver in addition to increment blood pressure, all components of the 'metabolic syndrome'.  This is caused specifically past times the fructose percentage of the sugar.
Here are the implications:
  1. Avoiding sugar-sweetened foods, in addition to specially sugar-sweetened beverages (soda, punch, sweetened coffee, cocktails, maybe fruit juice as well?) tin laissez passer the axe foreclose in addition to to some extent contrary obese gain in addition to metabolic dysfunction.
  2. I run across no argue to believe that refined in addition to unrefined sugars, used inwards the same context (e.g. muffins baked alongside white vs. chocolate-brown sugar), would remove hold dissimilar effects on torso fatness.  However, unrefined sugars may live on less harmful to other aspects of health, because they comprise other substances that may live on protective.  Mark Sisson discussed this thought inwards a recent post on beloved (38).  
  3. Eating fruit does non contribute to obese gain inwards most people, but instead belike favors leanness.  Fruit is a whole nutrient alongside a depression release energy density in addition to a moderate palatability in addition to vantage value.

* This is genuinely a fleck of an oversimplification.  Rats volition gorge themselves on this nutrient for virtually ii weeks, gain a bunch of torso fat, but in addition to so their nutrient intake returns to normal (this is presumably the release energy homeostasis organization kicking inwards as leptin in addition to insulin levels rise).  Despite the normalized calorie intake, they hold to gain obese at a slower rate.  Furthermore, they volition gain obese fifty-fifty if, from the real outset of the experiment, yous solely allow them to eat the same issue of calories as the regular unrefined chow grouping (39).  This shows that these diets are non but fattening because they travail increased nutrient intake-- it's to a greater extent than complicated than that.  This could yet live on explained past times the reward/palatability value of the diet, if nosotros invoke the thought that vantage in addition to hedonic centers deed on release energy homeostasis centers inwards the brain, favoring the 'defense' of a higher obese volume (40). But in that location are other contributing factors as well, such as the inflammation in addition to lipid accumulation that prepare inwards the hypothalamus in addition to lower leptin in addition to insulin responsiveness.



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