Time Restricted Feeding

Here’s an interesting study on High Fat diets and Time Restricted Feeding (Sherman H1, Genzer Y, Cohen R, Chapnik N, Madar Z, Froy O. Timed high-fat diet resets circadian metabolism and prevents obesity. FASEB J. 2012 Aug;26(8):3493-502. doi: 10.1096/fj.12-208868. Epub 2012 May 16.). The study

…tested whether long-term (18 wk) clock resetting by RF can attenuate the disruptive effects of diet-induced obesity.

The study looked at:

Analyses included liver clock gene expression, locomotor activity, blood glucose, metabolic markers, lipids, and hormones around the circadian cycle for a more accurate assessment.

Geneticaly, the study claims that:

Compared with mice fed the HF diet ad libitum, the timed HF diet restored the expression phase of the clock genes Clock and Cry1 and phase-advanced Per1, Per2, Cry2, Bmal1, Rorα, and Rev-erbα.

As far as weight goes:

Although timed HF-diet-fed mice consumed the same amount of calories as ad libitum low-fat diet-fed mice, they showed 12% reduced body weight, 21% reduced cholesterol levels, and 1.4-fold increased insulin sensitivity.

So, against a low fat diet the high fat diet did well. So far nothing new from usual. But what the study was concerned with was the Time Restricted Feeding (Intermittent Fasting) aspect. And that’s where the TRF diet did very well.

Compared with the HF diet ad libitum, the timed HF diet led to 18% lower body weight, 30% decreased cholesterol levels, 10% reduced TNF-α levels, and 3.7-fold improved insulin sensitivity. Timed HF-diet-fed mice exhibited a better satiated and less stressed phenotype of 25% lower ghrelin and 53% lower corticosterone levels compared with mice fed the timed low-fat diet. Taken together, our findings suggest that timing can prevent obesity and rectify the harmful effects of a HF diet.

Interesting results.

Here’s a related paper which notes a second study (Timed High Fat Diet Resets Circadian Metabolism and Prevents Obesity).

By an odd coincidence, a similar paper was published in the FASEB J2 about a month later, but the second paper didn’t seem to be aware of the first paper’s publication and didn’t cite it. In fact, the authors of the second paper thought that their paper was the first to be published on the subject of time restricted feeding of a high fat diet. 

Here’s the second paper (Hatori M, Vollmers C, Zarrinpar A, DiTacchio L, Bushong EA, Gill S, Leblanc M, Chaix A, Joens M, Fitzpatrick JA, Ellisman MH, Panda S. Time-restricted feeding without reducing caloric intake prevents metabolic diseases in mice fed a high-fat diet. Cell Metab. 2012 Jun 6;15(6):848-60). Here’s that abstract:

While diet-induced obesity has been exclusively attributed to increased caloric intake from fat, animals fed a high-fat diet (HFD) ad libitum (ad lib) eat frequently throughout day and night, disrupting the normal feeding cycle. To test whether obesity and metabolic diseases result from HFD or disruption of metabolic cycles, we subjected mice to either ad lib or time-restricted feeding (tRF) of a HFD for 8 hr per day. Mice under tRF consume equivalent calories from HFD as those with ad lib access yet are protected against obesity, hyperinsulinemia, hepatic steatosis, and inflammation and have improved motor coordination. The tRF regimen improved CREB, mTOR, and AMPK pathway function and oscillations of the circadian clock and their target genes’ expression. These changes in catabolic and anabolic pathways altered liver metabolome and improved nutrient utilization and energy expenditure. We demonstrate in mice that tRF regimen is a nonpharmacological strategy against obesity and associated diseases.

Sidenote

I was pointed to this by an article by Mark Hyman who claimed about the study that:

Note that the link is not to a human study but to the mouse study above. A tale of mice or men. Someone in a Facebook group pointed me to the study as proof that we can eat fat ad lib. LOL. Proves exactly the opposite.

Made the New York Times

With the bar so low on science reporting this article was a welcome sight (How a Low-Carb Diet Might Help You Maintain a Healthy Weight) particularly from the New York Times. Researcher David Ludwig and team did a pretty nice study this time aimed at using a low carb diet for weight maintenance. Of course being Dr Ludwig he was aiming to show a metabolic advantage to the Low Carb diet compared with other higher carb diets. And his results showed that advantage.

The study itself is (Ebbeling Cara B, Feldman Henry A, Klein Gloria L, Wong Julia M W, Bielak Lisa, Steltz Sarah K et al. Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial BMJ 2018; 363 :k4583) (full pdf).

The study participants were:

164 adults aged 18-65 years with a body mass index of 25 or more

The goal of the study was to determine if the total body energy expenditure (commonly referred to as “metabolism”) was increased on the Lower Carb intervention:

The primary outcome was total energy expenditure, measured with doubly labeled water, by intention-to-treat analysis. Per protocol analysis included participants who maintained target weight loss, potentially providing a more precise effect estimate.

Secondary outcomes were resting energy expenditure, measures of physical activity, and levels of the metabolic hormones leptin and ghrelin.

In other words, does Low Carb help with weight maintenance?
Most of us have lost quite a bit of weight in our lifetimes and found that our bodies want to return to that previous weight – plus some weight in most cases. Everyone recognizes that it’s a lot harder to maintain a weight loss than to lose weight.

I really like that the study wasn’t about weight loss with the usual advantages in the low carb diets due to higher glycogen losses. When people refer to water weight they rarely understand the good part of that water weight is two-fold. One is less inflammation – which is a good thing. The other is that the water comes out due to glycogen stores dropping. There’s 3-4 grams of water bound up with every gram of glycogen. Losing the glycogen is important for getting to visceral fat, particularly in the liver and pancreas.

Back to the study… The study controlled the one variable which everyone claims is the sole reason low carb diets do better – protein. The claim is that when protein is held equal low carb diets don’t beat other diets. But this study held protein the same between the interventions:

During the test phase, high, moderate, and low carbohydrate diets varied in carbohydrate (60%, 40%, and 20% of total energy, respectively) and fat (20%, 40%, and 60%, respectively), with protein fixed at 20%

Even the lowest level of 20% is a reasonably low carbohydrate diet. It wasn’t the typical 5% of the ketogenic diet. Not only did the study control for protein, it also controlled for added sugar, saturated fat and sodium. Nice touch.

The relative amounts of added sugar (15% of total carbohydrate), saturated fat (35% of total fat), and sodium (3000 mg/2000 kcal) were held constant across diets. 

Caloric intakes were adjusted to compensate for people continuing to drop weight.

The study had sufficient statistical power to tease out small differences between the groups that previous studies could not resolve (presumably the pilot Kevin Hall study which could not resolve differences due to lack of power (some of the conflict is documented by Dr Ludwig here).

The target of 135 completers provided 80% power, with 5% type I error, to detect a difference of 237 kcal/d in total energy expenditure change between one diet group and the other two diet groups. 

The results showed an increase in energy expenditure as a function of carbohydrate restriction. 

The difference in total energy expenditure was 209 to 278 kcal/d or about 50 to 70 kcal/d increase for every 10% decrease in the contribution of carbohydrate to total energy intake (1 kcal=4.18 kJ=0.00418 MJ).

Dr Hall, I think the ball is now in your court (Previous study)…

Update 2018-11-19: Kevin Hall has critiqued the methodology of this study: Kevin D Hall, Juen Guo, Kong Y Chen, Rudolph L Leibel, Marc L Reitman, Michael Rosenbaum, Steven R. Smith, Eric Ravussin. Methodologic Issues in Doubly Labeled Water Measurements of Energy Expenditure During Very Low-Carbohydrate Diets. bioRxiv 403931.

DLW calculations failing to account for diet-specific energy imbalance effects on RQ erroneously suggest that very low carbohydrate diets substantially increase energy expenditure.

Update 2018-12-01: Kevin Hall is going down swinging on this subject. Here’s some of the continuing controversy (Author Response to Hall and Guo Regarding Data Reanalysis and Other Criticisms).

The RCT That Will Never Happen

Here’s the Randomized Control Trial that I really want to see.

Take a lot of Type 2 Diabetics with BMIs in the obese range. Split them into two groups who are pair matched. Start one of the groups on Low Carb / High Fat diet and leave the control group on their customary Standard American Diet (SAD). Treat all of them with the standard of care as it is at the time. Track them for 40 years and look at the outcomes. Don’t just track some of the benchmarks like LDL cholesterol. Track all of their results including all-cause mortality. 

It won’t happen for too many reasons. And it doesn’t take a belief in conspiracy theories to figure out why. Perhaps the biggest reason is nobody makes money with Low Carb/High Fat and a study with sufficient statistical power would be very expensive.

In the meanwhile, we are all n=1. And none of us have 40 years. And no point in looking for the RCT above since it’s never going to happen. It would have had to start before anyone knew the right questions to ask.

How Low to Go?

I’ve done somewhere around 50 grams of carbohydrates a day (30 grams when subtracting out fiber) for the past year. And my blood sugar control has been great. I’ve wondered how low someone has to go (or stay) in order to control Type 2 Diabetes. Certainly, the weight loss I’ve had (120 lbs) is a part of the solution. Being at a low body fat percentage now (7.5% per BodPod) has to help as well. My weight has been stable for 6 months now as well which means I’ve not lost or gained any weight – I was at 164.7 lbs when I took the BodPod test and today I weighed 163.7 lbs (close enough). My coffee consumption (which helps in weight loss for sure) is higher than ever before but I’m trying to keep the caffeine down by mixing in mostly decaf coffee. 

So all of this begs the question of how many grams of carbs I could tolerate. Now, I am not going to be testing this anytime soon. I find the advantages of being low carb just way too easy (see above for the results). I did find a study that might provide at least a partial answer to the question of how many grams of carbs can keep someone in remission from Diabetes.

The answer is in this 2009 study (Haimoto H, Sasakabe T, Wakai K, Umegaki H. Effects of a low-carbohydrate diet on glycemic control in outpatients with severe type 2 diabetes. Nutr Metab (Lond). 2009 May 6;6:21).

Now, I wouldn’t even call this diet at 30% of calories from carbohydrates a “Low Carbohydrate” by any definition that I would recognize but it has interesting results. One of the things that was interesting is that the study was done on severe diabetics (HbA1c levels of 9.0% or above). This is not a group of new diabetics nor were the participants young. They were a pretty good representative of Type 2 Diabetics with poor blood sugar control. The participants:

were instructed to follow a low-carbohydrate diet (1852 kcal; %CHO:fat:protein = 30:44:20) for 6 months in an outpatient clinic and were followed to assess their HbA1c levels, body mass index and doses of antidiabetic drugs.

The results were really good. Many of the participants got off their medications and:

HbA1c levels decreased sharply from a baseline of 10.9 ± 1.6% to 7.8 ± 1.5% at 3 months and to 7.4 ± 1.4% at 6 months.

These are similar to the results I got with the Low Carbohydrate diet when I got to an HbA1c level of 6.4. They are not as good as the results I got over the last couple of years with even lower levels of carbohydrates plus intermittent fasting.

In spite of being on a fairly low calorie diet (1852 kcal) they didn’t lose much weight. This group also didn’t seem to be all that obese since their BMI was around 24 (top end of “normal” weight).

Body mass index decreased slightly from baseline (23.8 ± 3.3) to 6months (23.5 ± 3.4).

So, if you are “normal” weight and diagnosed as diabetic then dropping from the Standard American Diet (SAD) 50% of calories from carbohydrates to 30% might give as good of control as exogenous Insulin without the long term increase in insulin resistance that comes along with Insulin therapy.

There was one telling outlier in the data.

One female patient had an increased physical activity level during the study period in spite of our instructions. However, her increase in physical activity was no more than one hour of walking per day, four days a week. She had implemented an 11%-carbohydrate diet without any anti-diabetic drug, and her HbA1c level decreased from 14.4% at baseline to 6.1% after 3 months and had been maintained at 5.5% after 6 months.

Insulin Glucagon Glucose

Here’s a fun watch that is of interest to diabetics. And nerds.

On the Hyperlipid BLOG (Insulin glucagon and protein) examined this study (Unger RH, Cherrington AD. Glucagonocentric restructuring of diabetes: a pathophysiologic and therapeutic makeover. J Clin Invest. 2012 Jan;122(1):4-12). The study looked at Diabetes as a disorder more related to glucagon than insulin. In particular, the Hyperlipid BLOG considered the blood sugar response of a diabetic to protein. I did the same thing myself here in this BLOG several times (Glucose Response to ProteinBlood Sugar Response to Proteins and Blood Sugar Responses Compared).

The paper presents the following lines of evidence for the claim,

Here we propose that glucagon excess, rather than insulin deficiency, is the sine qua non of diabetes. We base this on the following evidence:

(a) glucagon increases hepatic glucose and ketone production, catabolic features present in insulin deficiency;

(b) hyperglucagonemia is present in every form of poorly controlled diabetes;

(c) the glucagon suppressors leptin and somatostatin suppress all catabolic manifestations of diabetes during total insulin deficiency;

(d) total β cell destruction in glucagon receptor-null mice does not cause diabetes; and (e) perfusion of normal pancreas with anti-insulin serum causes marked hyperglucagonemia.

The insight that this may not be as much an insulin issue as a glucagon issue is a powerful one which may have application with medications to control Type 2 Diabetes. If giving exogenous insulin produces problems with Insulin Resistance, giving a medication which causes the body to produce less glucagon may have an opposite effect. It may be possible to develop a medication which downregulates glucagon indefinitely.

This has been tried in a 2017 Phase I drug study (Glucagon-Blocking Drug Reduces Need for Insulin and Improves Blood Glucose Levels for Patients with Type 1 Diabetes). Here is the full paper for the study (Effect of a glucagon receptor antibody (Jeremy Pettus MD. REMD‐477) in type 1 diabetes: A randomized controlled trial).

What is the cost (in other systems in the body) if glucagon is downregulated? 

Is eating 50g of Whey Protein a good replacement for the OGTT? I think it’s a much better choice than eating 75g of glucose.

Mice on an Ad Lib Keto Diet

Here is a nice paper from 2009 on mice fed an ad libitum ketogenic diet (Kennedy AR, Pissios P, Otu H, Roberson R, Xue B, Asakura K, Furukawa N, Marino FE, Liu FF, Kahn BB, Libermann TA, Maratos-Flier E. A high-fat, ketogenic diet induces a unique metabolic state in mice. Am J Physiol Endocrinol Metab. 2007 Jun;292(6):E1724-39. Epub 2007 Feb 13).

The study looked at:

C57BL/6 mice animals were fed one of four diets:

1) KD;

2) a commonly used obesogenic high-fat, high-sucrose diet (HF);

3) 66% caloric restriction (CR); and

4) control chow (C).

Calories were the same but weight was lower on the ketogenic diet.

Mice on KD ate the same calories as mice on C and HF, but weight dropped and stabilized at 85% initial weight, similar to CR.

In fact, they moved mice from the High Fat High Carb diet to the Ketogenic diet and had the following:

Animals made obese on HF and transitioned to KD lost all excess body weight, improved glucose tolerance, and increased energy expenditure. 

Even more along my own area of interest:

KD fed mice had a unique metabolic and physiological profile, exhibiting increased energy expenditure and very low respiratory quotient

The macronutrient composition of the diets was interesting:

MacroChowHFKD
Fat16.7%45%95.00%
Protein26.80%24%0%
Carbs56.40%35%5%

Note this was not a high protein KD. I.e., The dietary advantage wasn’t protein. The percentage of calories from protein was the lowest on the KD – by far. This is a much higher level of fat than most people will tolerate and the protein level is pretty low.

Most telling was the body composition changes (Table 5).

DEXAChowKDHF
Fat4.545.1613.27
Lean28.9823.8530.59
Mass33.5229.0143.86
%BF13.5%17.8%30.3%

The Chow fed mice were a bit over 10% heavier but at a lower % of Body Fat (13.5%) vs the Ketogenic fed mice. This can be attributed to the much lower protein consumption of the KD.

A contrasting study (Protein Leverage Hypothesis Counterpoint) showed an inflection point around 70% for fat where additional fat did not result in additional weight. In my opinion (study needed) – substituting protein for some of the fat should not be an issue.

The study concluded:

the effects that diet composition can have on metabolism and found that diets high in fat and low in carbohydrate do in fact lead to weight loss by increasing energy expenditure. 

Remarkably, animals eating ketogenic diet lost a small amount of weight and achieved the same weight and body composition as animals that were calorie restricted to 66% of usual daily intake.

In a related paper (Bielohuby M1, Menhofer D, Kirchner H, Stoehr BJ, Müller TD, Stock P, Hempel M, Stemmer K, Pfluger PT, Kienzle E, Christ B, Tschöp MH, Bidlingmaier M. Induction of ketosis in rats fed low-carbohydrate, high-fat diets depends on the relative abundance of dietary fat and protein. Am J Physiol Endocrinol Metab. 2011 Jan;300(1):E65-76) noted the same issue with KD :

One problem with ketogenic LC-HF diets is that it is difficult to attribute observed effects (e.g., loss of body weight) to either the presence of ketone bodies or to the normally very low protein content of these diets.

The ideal ketogenic diet for research purposes would be a LC-HF diet that is ketogenic but ensures the sufficient supply of protein at the same time. However, until now, it is not clear whether the absence of dietary carbohydrates per se or the absence of carbohydrates in combination with a specific abundance of the two other macronutrients, fat and protein, is required to induce ketosis.

Fat Stores Where/How?

Peter at the Hyperlipid BLOG has an interesting analysis of an interesting paper on fat storage in mice (On phosphorylating AKT within visceral fat). The study he looks at is (Narita T, Kobayashi M, Itakura K, Itagawa R, Kabaya R, Sudo Y, Okita N, Higami Y. Differential response to caloric restriction of retroperitoneal, epididymal, and subcutaneous adipose tissue depots in rats.  Exp Gerontol. 2018 Apr;104:127-137). The study looked at ad lib feeding of mice and the storage of fat in three White Adipose Tissues (WAT) depots in rats: retroperitoneal (rWAT), epididymal (eWAT) and subcutaneous (sWAT).

Peter’s interest is in fat storage based on insulin levels. The study compared ad libitum to calorie restricted eating in the mice. Peter concentrated on the ad libitum eating of the mice (not being all that interested in calorie restricted diets). Peter points out that it takes insulin to store fat in subcutaneous tissues but very little insulin to store fat in visceral fat. The study put it this way:

In all WAT depots, CR markedly upregulated the expression of proteins involved in FA biosynthesis in fed rats. In visceral WAT (rWAT and eWAT), hormone-sensitive lipase (lipolytic form) phosphorylation was increased by CR under fed conditions, and decreased by CR under fasted conditions. Conversely, in sWAT, hormone-sensitive lipase phosphorylation was increased by CR under fasted conditions. CR enhanced the effect of feeding on AKT activity in sWAT (indicative of a positive effect on insulin sensitivity) but not in rWAT or eWAT. These data suggest that CR improves lipid metabolism in an insulin signaling-dependent manner in sWAT only.

As Peter puts it:

This looks very much like one of the intrinsic differences between subcutaneous adipocytes and visceral adipocytes is that visceral adipocytes maintain insulin signalling at much lower levels of plasma insulin than do subcutaneous adipocytes. You have to store calories which arrive without insulin somewhere. Looks like this is the place!

I’m still of the opinion that visceral fat is what matters the most in reversal of Type 2 Diabetes. The Low Carb diet gets insulin levels low which reduces fat in general. See this article (A Grand Unified Theory of Polyunsaturated Fatty Acid Misbehaviour in Inflammatory Disease).

This article is actionable as well (Fatty liver and its treatment).

Alcohol and Weight Loss

I get asked a lot about alcohol and weight loss. Here’s a study which took a look at what happens to fat oxidation when alcohol is consumed (Siler SQ, Neese RA, Hellerstein MK. De novo lipogenesis, lipid kinetics, and whole-body lipid balances in humans after acute alcohol consumption. Am J Clin Nutr. 1999 Nov;70(5):928-36).

OBJECTIVE:

We used stable-isotope mass spectrometric methods with indirect calorimetry to establish the metabolic basis of changes in whole-body lipid balances in healthy men after consumption of 24 g alcohol.

DESIGN:

Eight healthy subjects were studied and DNL (by mass-isotopomer distribution analysis), lipolysis (by dilution of [1,2,3,4-(13)C(4)]palmitate and [(2)H(5)]glycerol), conversion of alcohol to plasma acetate (by incorporation from [1-(13)C(1)]ethanol), and plasma acetate flux (by dilution of [1-(13)C(1)]acetate) were measured.

RESULTS:

The fractional contribution from DNL to VLDL-triacylglycerol palmitate rose after alcohol consumption from 2 +/- 1% to 30 +/- 8%; nevertheless, the absolute rate of DNL (0.8 g/6 h) represented <5% of the ingested alcohol dose; 77 +/- 13% of the alcohol cleared from plasma was converted directly to acetate entering plasma. Acetate flux increased 2.5-fold after alcohol consumption. Adipose release of nonesterified fatty acids into plasma decreased by 53% and whole-body lipid oxidation decreased by 73%.

CONCLUSIONS:

We conclude that the consumption of 24 g alcohol activates the hepatic DNL pathway modestly, but acetate produced in the liver and released into plasma inhibits lipolysis, alters tissue fuel selection, and represents the major quantitative fate of ingested ethanol.

It’s not so much that the alcohol itself gets turned to fat, it’s that alcohol inhibit lipolysis (fat burning).