Ultra-high-fat (~80%) diets: Fat storage, and a delicious analogy.

Fat storage:

Here's a plot of mean (±SEM) plasma insulin concentrations during an oral-glucose-tolerance test (OGTT) when preceded by either a high-fat (▪) or a high-carbohydrate (□) evening meal and during an oral-fat-tolerance test (OFTT) when also preceded by either a high-fat (•) or a high-carbohydrate (○) evening meal.

From Extended effects of evening meal carbohydrate-to-fat ratio on fasting and postprandial substrate metabolism

100g of glucose produces a large spike in insulin concentration and 40g of fat produces no significant spike in insulin concentration. According to Gary Taubes' insulin hypothesis of obesity, in the absence of a significant spike in insulin concentration, fat cannot be stored.

Here's a plot of mean (±SEM) plasma triacylglycerol concentrations during an oral-fat-tolerance test (OFTT) when preceded by either a high-fat (•) or a high-carbohydrate (○) evening meal (from the previous post).

From Extended effects of evening meal carbohydrate-to-fat ratio on fasting and postprandial substrate metabolism

Average plasma triacylglycerol concentration over 0 to 360min is ~1.3mmol/L (~116mg/dL in US units).

Plasma triacylglycerol concentration falls to baseline between 240min and 360min. OGTT's and OFTT's are performed with the subjects at rest for the duration of the test.

Referring to It's all in a day's work (as measured in Joules) , at rest the subject is burning ~1kcal/min with ~95% of it coming from fat, making a fat-burning rate of ~0.11g/min.

At a fat-burning rate of ~0.11g/min, it would take ~360min for plasma triacylglycerol to fall to baseline if the 40g of fat from the OFTT was only being burned and not being stored. As shown above, it only takes ~120min to fall to baseline. Therefore, fat from the OFTT that isn't burned is stored in ~120min in the absence of a significant insulin spike. Q.E.D.

A delicious analogy:

Here's a plot of mean (±SEM) plasma glucose concentrations during an oral-glucose-tolerance test (OGTT) when preceded by either a high-fat (▪) or a high-carbohydrate (□) evening meal and during an oral-fat-tolerance test (OFTT) when also preceded by either a high-fat (•) or a high-carbohydrate (○) evening meal (from the previous post).

From Extended effects of evening meal carbohydrate-to-fat ratio on fasting and postprandial substrate metabolism

The OGTT (100g of glucose) produces a large spike in plasma glucose concentration which lasts for ~210min before returning to baseline. Higher plasma glucose concentrations glycate more than lower plasma glucose concentrations. Average plasma glucose concentration over 0 to 360min is higher with the OGTT than with the OFTT, therefore there is more glycation damage with the OGTT than with the OFTT. Don't regularly consume 100g or more of glucose!

Here's a plot of Mean (±SEM) plasma triacylglycerol concentrations during an oral-glucose-tolerance test (OGTT) when preceded by either a high-fat (▪) or a high-carbohydrate (□) evening meal.

From Extended effects of evening meal carbohydrate-to-fat ratio on fasting and postprandial substrate metabolism

Average plasma triacylglycerol concentration over 0 to 360min is ~1.0mmol/L (~89mg/dL in US units).

Although the plasma triacylglycerol concentration after consuming a high-carbohydrate evening meal is slightly higher than after consuming a high-fat evening meal, the two plots above are essentially flat, indicating that none of the 100g of glucose consumed was turned into fat by de novo lipogenesis (DNL) within 6 hours.

As discussed in the previous post, higher plasma triacylglycerol concentrations are more atherogenic than lower plasma triacylglycerol concentrations. Average plasma triacylglycerol concentration over 0 to 360min is higher with the OFTT than with the OGTT, therefore there is more atherogenicity with the OFTT than with the OGTT.
Don't regularly consume 40g or more of fat!

An interesting study that involved humongous fat consumption was Response of body weight to a low carbohydrate, high fat diet in normal and obese subjects , which used up to 600g of fat/day. It's possible to lose weight on an ultra-high-fat diet, but average plasma triacylglycerol concentrations would have been extremely high. Fasting TG's reduce on an ultra-high-fat diet, probably due to suppression of endogenous TG synthesis by exogenous TG intake.

Ultra-high-fat (~80%) diets: The good, the bad and the ugly.

The good:

Here's a plot of mean (±SEM) plasma glucose concentrations during an oral-glucose-tolerance test (OGTT) when preceded by either a high-fat (▪) or a high-carbohydrate (□) evening meal and during an oral-fat-tolerance test (OFTT) when also preceded by either a high-fat (•) or a high-carbohydrate (○) evening meal (Fig. 1).

Fig. 1 from Extended effects of evening meal carbohydrate-to-fat ratio on fasting and postprandial substrate metabolism

An OGTT (100g of glucose dissolved in water) causes a short-term increase in blood glucose level. Ditto for insulin (see Fig. 2 ▪ & □ below).

Fig. 2 from Extended effects of evening meal carbohydrate-to-fat ratio on fasting and postprandial substrate metabolism

An OFTT (40g of fat as cream) doesn't cause a significant increase in blood glucose level (see Fig. 1 • & ○ above). Ditto for blood insulin (see Fig. 2 • & ○ above).

The bad:

Here's a plot of mean (±SEM) plasma triacylglycerol concentrations during an oral-fat-tolerance test (OFTT) when preceded by either a high-fat (•) or a high-carbohydrate (○) evening meal (Fig. 3).

Fig. 3 from Extended effects of evening meal carbohydrate-to-fat ratio on fasting and postprandial substrate metabolism

An OFTT (40g of fat as cream) causes a significant increase in blood triacylglycerol (a.k.a. TAG a.k.a. triglyceride a.k.a. TG) level for 3 hours. Note that the effect of a preceding high-carbohydrate meal on fasting TG is only +0.1mmol/L. Is high postprandial TG a problem? Definitely, maybe. From Cholesterol And Coronary Heart Disease , "Cholesterol-depleted particles oxidise faster than large, cholesterol-rich ones." Chylomicrons, chylomicron remnants & VLDL-C are triglyceride-rich, cholesterol-poor, as that's the composition of the fat in the diet.

The ugly:

Here's evidence that high postprandial TG is atherogenic. See Fig. 1 in Fasting Compared With Nonfasting Triglycerides and Risk of Cardiovascular Events in Women.

People who have Insulin Resistance &/or type 2 diabetes have impaired postprandial clearance of glucose and TG, which is atherogenic. Lifestyle Intervention Leading to Moderate Weight Loss Normalizes Postprandial Triacylglycerolemia Despite Persisting Obesity.

Here's evidence that postprandial saturated fat TG is atherogenic. Postprandial triglyceride-rich lipoproteins promote invasion of human coronary artery smooth muscle cells in a fatty-acid manner through PI3k-Rac1-JNK signaling.

See also:-
Postprandial triglyceride-rich lipoprotein changes in elderly and young subjects.,
Effect of a single high-fat meal on endothelial function in healthy subjects.,
Postprandial lipemia: emerging evidence for atherogenicity of remnant lipoproteins.,
Alimentary lipemia, postprandial triglyceride-rich lipoproteins, and common carotid intima-media thickness in healthy, middle-aged men.,
Evidence for a cholesteryl ester donor activity of LDL particles during alimentary lipemia in normolipidemic subjects.,
Association of postprandial hypertriglyceridemia and carotid intima-media thickness in patients with type 2 diabetes.,
Postprandial hypertriglyceridemia impairs endothelial function by enhanced oxidant stress.,
High-energy diets, fatty acids and endothelial cell function: implications for atherosclerosis.,
Impact of postprandial hypertriglyceridemia on vascular responses in patients with coronary artery disease: effects of ACE inhibitors and fibrates.,
[Influence of postprandial hypertriglyceridemia on the endothelial function in elderly patients with coronary heart disease].,
Impact of postprandial variation in triglyceridemia on low-density lipoprotein particle size.,
Association between fasting and postprandial triglyceride levels and carotid intima-media thickness in type 2 diabetes patients.,
[Correlation of lipemia level after fat loading with manifestation of atherosclerosis in coronary arteries].,
Postprandial hypertriglyceridemia and carotid intima-media thickness in north Indian type 2 diabetic subjects.,
Association between postprandial remnant-like particle triglyceride (RLP-TG) levels and carotid intima-media thickness (IMT) in Japanese patients with type 2 diabetes: assessment by meal tolerance tests (MTT).,
Postprandial lipemia and remnant lipoproteins., 
Elevated levels of platelet microparticles in carotid atherosclerosis and during the postprandial state.,
Postprandial metabolic and hormonal responses of obese dyslipidemic subjects with metabolic syndrome to test meals, rich in carbohydrate, fat or protein.,
Atherosclerosis, diabetes and lipoproteins., 
Clinical relevance of non-fasting and postprandial hypertriglyceridemia and remnant cholesterol.,
Post-prandial hypertriglyceridemia in patients with type 2 diabetes mellitus with and without macrovascular disease.,
A hypertriglyceridemic state increases high sensitivity C-reactive protein of Japanese men with normal glucose tolerance.,
CD36 inhibitors reduce postprandial hypertriglyceridemia and protect against diabetic dyslipidemia and atherosclerosis., 
[Trends of evaluation of hypertriglyceridemia -from fasting to postprandial hypertriglyceridemia-].,
The effects of dietary fatty acids on the postprandial triglyceride-rich lipoprotein/apoB48 receptor axis in human monocyte/macrophage cells.

See also What Is the Significance of Postprandial Triglycerides Compared With Fasting Triglycerides? and Uncovering a Hidden Source of Cardiovascular Disease Risk.

A counter-argument is that the subjects in the above studies were eating carbohydrate, and that postprandial TG isn't atherogenic if you're not eating much carbohydrate. Definitely, maybe. In the absence of carbohydrates, there is still glucose in the blood, thanks to the liver and kidneys. Also, some carbohydrates don't spike blood glucose (or fructose) level. It's pure speculation that the subjects in the above studies had high blood glucose at the same time as high postprandial TG. As Insulin Resistance/Metabolic Syndrome and/or a high-sugar diet raise fasting TG, and there was no significant association between fasting TG and the risk factor for CHD, this suggests that the subjects had no significant metabolic derangement and were not eating excessive amounts of sugar.

According to Very Low-Carbohydrate and Low-Fat Diets Affect Fasting Lipids and Postprandial Lipemia Differently in Overweight Men, there's a ~50% reduction in postprandial TG after adaptation to a low-carb, high-fat diet. However, mean energy intake was 1,850kcals/day, the subjects were in a 500kcal/day energy deficit and %E from fat was 60%.

Some people's LDL becomes very high on low-carbohydrate high-fat diets. See Some Metabolic Changes Induced by Low Carbohydrate Diets.

It's possible to get Coronary Artery Calcium (CAC) scans, to measure the amount of calcified plaque in coronary arteries. While a high CAC value means lots of plaque, a zero CAC value doesn't necessarily mean zero plaque, as young people and people with a high Vitamin K2 intake don't have significant calcification. See Stenosis Can Still Exist in Absence of Coronary Calcium.

See also Page 10 of  HIGH CARBOHYDRATE DIETS: MALIGNED AND MISUNDERSTOOD - Nathan Pritikin.
"Could such a cream meal precipitate an angina attack because the oxygen-carrying capacity of the blood is lowered?"
The answer is "Yes."

Diogenes: High protein + low GI = Weight-loss maintenance WIN.

See Diets with High or Low Protein Content and Glycemic Index for Weight-Loss Maintenance.

LP = Low Protein. HP = High Protein. LGI = Low GI. HGI = High GI.

"In conclusion, in this large, randomized study, a diet that was moderately high in protein content and slightly reduced in glycemic index improved the rate of completion of the intervention and maintenance of weight loss and therefore appears to be ideal for the prevention of weight regain."

Note that Low GI isn't the same as Low carb. The Low GI diets had ~43% of total energy from carbohydrate. The Low GI diets were not Low carb diets. They weren't as High carb as Healthy Eating Guidelines (55% of total energy from carbohydrate).

How to lose body-fat healthily.

Previous blog posts have been about Carbohydrates, Fats & Proteins. However, when you go shopping, you buy food. So this blog post is going to be about food. Updated!

1) If you're eating a high-carb diet, eat 6 small meals or 3 meals and 3 snacks per day to keep your blood glucose relatively stable. I used to believe that it also kept your metabolic rate high, but I now know this to be a myth. If you're the type of person who gets lowish blood glucose in the mornings (which may make you ravenously hungry and therefore highly likely to buy junk food when you're away from home), skipping breakfast is not advisable. If you're the type of person who isn't satisfied by small meals/snacks, a small number of large meals (Intermittent Fasting) is a better option.

2) Meals and snacks should contain proteins, fats and fibrous carbs.

3) Slow sugary/starchy carbs can be eaten in meals/snacks at breakfast and before/after workouts/exercise/intense activity. If/when you are sedentary, keep slow sugary/starchy carbs to a minimum. Keep fast sugary/starchy carbs to a minimum (except for the occasional treat or post-workout) as they can cause large fluctuations in blood glucose and insulin levels. The more intense exercise you do, the more slow sugary/starchy carbs you can eat.

4) Drink >1.5 litres of no-added-sugar watery drinks per day. If your urine is darker than straw, drink more. If you're weeing too often, drink less.

5) Balance your omega-6 and omega-3 essential fatty acids (EFAs) by eating about 100g of omega-3 rich oily fish (sild, sardines, pilchards, mackerel, herring, salmon, trout, fresh tuna etc) per day or supplement with fish oil capsules such that you get at least 2g of EPA+DHA per day. Please note that tinned tuna contains virtually zero omega-3 fat.

If you're vegetarian or vegan, see Vegetarians & vegans, listen up!

6) Eat 2 to 3 portions of low-sugar fruits per day - preferably before meals/snacks. Minimise your consumption of high-sugar fruits.

Proteins are:- Meats, poultry, fish, eggs, cheese, Quorn, seeds, nuts, legumes (peas, beans & lentils).

Fibrous carbs are:- All vegetables that grow above ground level, bulbs (onions, leeks, garlic etc) and "vegetable" fruits (tomatoes, peppers, cucumbers/courgettes, aubergines, avocados, olives etc).
Slow sugary/starchy carbs are:- All-bran, no-added-sugar muesli, oats, sweet potatoes, lightly-boiled new potatoes eaten hot, cold or refrigerated, Basmati rice, non-overcooked legumes & root veggies, lumpy wholegrain rye breads, Burgen/Vogel's soya & linseed breads.

Fast sugary/starchy carbs are:- White wheat breads, wholemeal wheat breads, most breakfast cereals including Shredded Wheat, Weetabix, Cheerios, Grapenuts etc, sugar, sweets, chocolate, cakes, biscuits, cereal bars, sweetcorn, overcooked tubers e.g. jacket potatoes, overcooked root veggies, overcooked legumes e.g. baked beans.

High sugar fruits are:- Ripe & over-ripe bananas, grapes, pineapples, sweet apples, sweet pears, sultanas, raisins, currants and any dried fruits with added sugar.

Low sugar fruits are:- Berries, stone fruits, citrus, Granny Smith apples, Conference pears. Dried apple rings, apricots, pear halves, peach halves and prunes without added sugar are high in sugar but they release that sugar very slowly.

Fats are sats, monos and the EFAs mentioned above. Butter is high in sats and monos. Olive oil & spreads are high in monos. Sunflower/safflower/corn oils & spreads are very high in omega-6 EFAs - minimise your consumption of these. Don't fry or roast with high-EFA oils as they oxidise and convert into trans-fats too quickly. Meats contain sats, monos and some EFAs. Minimise your consumption of anything with the word "hydrogenated" in the ingredients list.

Some foods fall in-between categories like yellow bananas which are medium speed sugary/starchy carbs. Green bananas are slow carbs and black bananas are fast carbs.

Depending on your insulin sensitivity, speed of metabolism and exercise levels, you may get away with eating fast sugary/starchy carbs - you'll just have to "suck it and see".

If eating makes you feel drowsy followed by hunger, you probably have Insulin Resistance. See Insulin Resistance: Solutions to problems. for ways to reverse Insulin Resistance.

One final bijou tip-ette:- Avoid walking down "dodgy" supermarket aisles (confectionery, cereals, booze, fizzy drinks) as "What the eye don't see, the heart don't grieve over".

Happy New Year folks!

Cont'd on How to lose body-fat healthily, Part 2.