New Study on Insulin, Genes, and Diet

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New Study on Insulin, Genes, and Diet

Post by sharperhawk on Wed Feb 21, 2018 12:25 pm

A new study sponsored by NuSI, Gary Taubes' research foundation, has been published in JAMA. The lead author is Christopher Gardner, whom you may know from his "A to Z" diet study. The new study compared low-fat and low-carb diet interventions and also took genetic markers and insulin response to see whether those would predict how much weight people lost.

A post on has an excellent write-up for a general audience: Low-fat vs low-carb? Major study concludes: it doesn’t matter for weight loss. It has some nice graphs and an interview with Gardner.

The study is titled "Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial." Below is the abstract.
IMPORTANCE Dietary modification remains key to successful weight loss. Yet, no one dietary strategy is consistently superior to others for the general population. Previous research suggests genotype or insulin-glucose dynamics may modify the effects of diets.

OBJECTIVE To determine the effect of a healthy low-fat (HLF) diet vs a healthy low-carbohydrate (HLC) diet on weight change and if genotype pattern or insulin secretion are related to the dietary effects on weight loss.

DESIGN, SETTING, AND PARTICIPANTS The Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) randomized clinical trial included 609 adults aged 18 to 50 years without diabetes with a body mass index between 28 and 40. The trial enrollment was from January 29, 2013, through April 14, 2015; the date of final follow-up was May 16, 2016. Participants were randomized to the 12-month HLF or HLC diet. The study also tested whether 3 single-nucleotide polymorphism multilocus genotype responsiveness patterns or insulin secretion (INS-30; blood concentration of insulin 30 minutes after a glucose challenge) were associated with weight loss.

INTERVENTIONS Health educators delivered the behavior modification intervention to HLF (n = 305) and HLC (n = 304) participants via 22 diet-specific small group sessions administered over 12 months. The sessions focused on ways to achieve the lowest fat or carbohydrate intake that could be maintained long-term and emphasized diet quality.

MAIN OUTCOMES AND MEASURES Primary outcome was 12-month weight change and determination of whether there were significant interactions among diet type and genotype pattern, diet and insulin secretion, and diet and weight loss.

RESULTS Among 609 participants randomized (mean age, 40 [SD, 7] years; 57% women; mean body mass index, 33 [SD, 3]; 244 [40%] had a low-fat genotype; 180 [30%] had a low-carbohydrate genotype; mean baseline INS-30, 93 μIU/mL), 481 (79%) completed the trial. In the HLF vs HLC diets, respectively, the mean 12-month macronutrient distributions were 48% vs 30% for carbohydrates, 29% vs 45% for fat, and 21% vs 23% for protein. Weight change at 12 months was −5.3 kg for the HLF diet vs −6.0 kg for the HLC diet (mean between-group difference, 0.7 kg [95% CI, −0.2 to 1.6 kg]). There was no significant diet-genotype pattern interaction (P = .20) or diet-insulin secretion (INS-30) interaction (P = .47) with 12-month weight loss. There were 18 adverse events or serious adverse events that were evenly distributed across the 2 diet groups.

CONCLUSIONS AND RELEVANCE In this 12-month weight loss diet study, there was no significant difference in weight change between a healthy low-fat diet vs a healthy low-carbohydrate diet, and neither genotype pattern nor baseline insulin secretion was associated with the dietary effects on weight loss. In the context of these 2 common weight loss diet approaches, neither of the 2 hypothesized predisposing factors was helpful in identifying which diet was better for whom.

The diet comparison has been done several times before. The insulin response tests an interesting hypothesis: maybe insulin-resistant people do better on low carb. These data say no difference. I am not familiar with the genetic markers used; the null results may just mean that some different set of genes will prove useful in matching person to diet.

Another point of interest is that both diet interventions emphasized whole foods and neither involved counting calories. Previous studies typically compare Atkins (low-carb, ad libitum, processed foods) with Ornish (low-fat, calorie counting, whole foods), so this new one did a better job of looking only at macro differences.

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Re: New Study on Insulin, Genes, and Diet

Post by Ellito on Thu Mar 01, 2018 2:37 pm

They actually compared the diets fairly. Usually the low-carb diet is less than 20 grams of carbs and the "low" fat diet is still 30% fat. In this study, "low" actually meant 30%, for both groups.

I like it.


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Re: New Study on Insulin, Genes, and Diet

Post by Lovebird on Thu Jun 21, 2018 1:33 pm

"Dawn learned this from the researchers, who described quality nutrition to the study participants this way:

   ... focus on whole, real foods that were mostly prepared at home when possible, and specifically included as many vegetables as possible, every day ... choose lean grass-fed and pasture-raised animal foods as well as sustainable fish ... eliminate, as much as possible, processed food products, including those with added sugars, refined white flour products, or trans-fats ... prepare as much of their own food as possible. ... "

"Interestingly, the focus on quality did not work for Denis and Elizabeth, the pair who did not lose much or even gained in the study. Denis felt he had a hard time saying no to junk foods and didn’t have enough time and motivation to prepare healthy alternatives consistently. He also felt frustrated by the fact that he struggled to apply everything he learned about nutrition. Elizabeth, meanwhile, felt she could have used more advice on how to cut calories and portion sizes, instead of all the focus on eating healthy foods. "

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Re: New Study on Insulin, Genes, and Diet

Post by LoonieJ on Sat Jul 28, 2018 5:16 pm

Way late to the party..

I feel for Denis and Elizabeth.

Denis' reason sounds a little whine-y, but if you're going to help someone lose weight, you really can't use a one size fits all approach. Dude likes his s*it food. We start there. Instead of making every junk food a fail for him, show him the frozen food section. Teach him to read labels. We can get to grass-fed eventually, but you're not going to change this man's pallet overnight.

Just an example... How about as a first step, we steer him away from chain "restaurants" like McGarbage? He can buy pre-formed burger patties, stock up on burger buns, and his favorite fixin's. And though I loathe them, we show him frozen French fries. Not the best, nutritionally, but we have him in the kitchen, and preparing burgers and fries this way is easy. Once he's acclimated to cooking this way, we can show him burger in bulk and teach him to save money. If he can afford it, we later show him the wonders of pastured/organic/grass-fed ground beef.

Not ready to cook chicken yet? And Costco (and tons of other stores) said, "Let there be rotisserie," and it was good. I've even seen sort of instant rice stuff that you heat up in the microwave. Again, not perfect, but definitely a few steps up from chicken nuggets from a drive-through.

IOW, some people change through a radical shift, and some people change through baby steps. And we teach him not to self-shame. You fall off the wagon? You get back on by the next meal.

For Elizabeth, I'd teach her how to read labels and how to look up calories/nutritional info online. I would make sure that she had measuring spoons, measuring cups, and one of my favorite things to teach me how to visualize portion size: a kitchen scale. Then depending on how detail oriented she was, I'd teach her to plan her day's meals over coffee. Not only does this give her a blueprint for the day, but she knows what to take out of the freezer in the morning.

Here's a little tale. Back in college I let my weight get up to a whopping 156 lbs. "OMG!" I wailed to my BFF, "What will I do?" "Go on a diet," she said, calmly. I had always thought "diets" were for women who lived on cul de sacs.

So, with nary a thought of nutrition in my head, I created my own LoonieJ diet. One meal/day. Supper was the only meal I cared about, so supper it was. I didn't count calories, I didn't increase exercise. My average day was something like: 3 double lattes with whole milk, and a half of an extra-large pepperoni, mushroom, and cheese pizza. Sometimes Chinese takeout, sometimes a hero/sub sandwich.

I would have cooked more often except one day my boyfriend and I had a huge argument because he wasn't doing his fair share of the dishes. I let them pile up for four days, then threw them out. There really wasn't much to cook with nor eat off, so whatever. Cool

Anyway, I went from 156 lbs to 118 lbs in just under seven weeks.

The only weight loss plan that works is the one you can stick with for as long as you need to get the weight off. If that means drinking a can of sugar soda (I picked something I really don't like) every day, then so be it.

As always, JMO.

Peace, love and body acceptance,

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Re: New Study on Insulin, Genes, and Diet

Post by Annieh on Sun Jul 29, 2018 12:37 am

Nice comments Joanie, it seems that both Denis and Elizabeth have correctly identified where they went wrong and i love your plan for Dennis, it would surely help.

As for Elizabeth, if she actually was already doing much of what was advised regarding quality, then yes, she needed the kind of help she was asking for.  How hard could it have been to tell her, see here's the size your plate should be, put so much meat and so many veggies on it and you're good to go.

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