Didn't the low fat diet fail?

The largest test of it did. 48,835 women past menopause were assigned for an average of 8.1 years. Heart disease, stroke, all heart and blood vessel disease, and invasive breast cancer all showed no difference, and LDL fell only 3.55 mg/dL. What it did not do is cause harm or weight gain, which was an open question at the time. And a different approach, cutting saturated fat rather than total fat, did cut heart attacks, strokes and other heart events combined by 17 percent across 15 studies.

But at the same calories, is low fat better than low carb?

For body fat loss, yes, by an amount too small to plan around. In a hospital research unit with food fixed, cutting fat led to 89 g a day of body fat loss, against 53 g a day from cutting carbs. That is a real difference of about 36 grams of fat a day. It is also the opposite of what the carbohydrate-insulin model predicts, which is why it gets quoted so often.

What about the Ornish reversal trial?

It is real, and it is not a diet trial. 48 people were assigned to a package: a 10 percent fat vegetarian diet plus aerobic exercise, stress management, quitting smoking and group support. 35 finished five years of artery scans. Artery narrowing eased in the program group and got much worse in the control group, and the program group had roughly half the rate of heart events. Which of the five parts did that has never been measured. The study was small, and it ran from 1986 to 1992, before today's statins and artery-opening procedures.

Will I lose weight on it?

Against doing nothing, yes, about 5.4 kg in the pooled studies. Against another real weight loss diet of similar effort, no difference at all, and a low carb diet beats it by 1.15 kg. In the four-group study that set fat at 20 to 40 percent of calories with calories matched, both groups lost 3.3 kg at two years. How many group sessions people went to predicted the result better than the diet mix did.

Who does this pattern suit least?

People whose cholesterol problem is high triglycerides with low HDL. At steady weight this diet did little or nothing for triglycerides. In the pooled studies, the higher fat diets won by the most exactly where the triglyceride gap at follow-up was widest. That is the clearest sign anywhere in this section that low fat and low carb suit different people.

Macronutrient-defined12 studies in people cited

Low fat

Written by Aaron CuhaReviewed Sep 2026

Also called: Low fat diet, Ornish, Lifestyle Heart programme, Plant-based low fat

The largest diet trial ever run put 48,835 women on it for eight years. It found no drop in heart disease, stroke or breast cancer. At fixed calories it beats cutting carbs for fat loss. Against other real diets it beats none of them.

What it actually is

Cutting total fat, usually to 20 to 30 percent of calories. The version most people mean when they say the diet failed is the public health version: around 20 percent of calories from fat, with more grains, fruit and vegetables. The version with the famous artery scans is a different thing. The Ornish Lifestyle Heart program runs about 10 percent of calories from fat on a whole foods vegetarian diet, and it was never tested as a diet. It was tested as a five-part package that also included aerobic exercise, stress management training, quitting smoking and group support. Nobody has separated the diet from the other four parts, so every claim made for the Ornish result is a claim about the whole package.

How its fans say it works

There are two arguments, and they should be kept apart, because the evidence treats them differently. The first is about calories. Fat carries nine calories per gram, against four for carbs and protein. So cutting fat makes food less calorie-dense and should cut how much you eat without counting portions. The second is about cholesterol. Saturated fat raises LDL, LDL clogs arteries, and so cutting fat should lower LDL and with it heart attacks and strokes. The second argument is specific, and it has been tested against real heart outcomes, which is more than most diet ideas can say. The answer depends a lot on whether a study cut total fat or targeted saturated fat, and those two came out differently.

What happened when calories were controlled

Best kind of study available: calories matched

Both groups ate the same number of calories, so a difference comes from what was in the diet, not how much people ate.

At the same calories, cutting fat leads to more body fat loss than cutting carbs. That is the opposite of the popular claim, and the effect is tiny either way. Against other real diets of similar effort, there is no weight advantage at all. The diet's real calorie finding came from people eating freely: in a hospital unit, people offered a low fat plant-based diet ate 689 calories a day less than on a keto diet.

Tobias 2015 pooled 53 trials with 68,128 people that compared low fat against something else for at least a year. Low carb diets beat low fat by 1.15 kg, with a likely range of 0.52 to 1.79 kg. Low fat did not differ at all from other higher fat weight loss diets (0.36 kg, too small to be real). Low fat beat a usual diet by 5.41 kg. The authors' own reading is the useful one: how well a low fat diet seems to work depends almost entirely on how much effort went into the comparison group.
The saturated fat question is separate, and it comes out differently. A 2020 Cochrane review of 15 trials with 56,675 people found that cutting saturated fat cut heart attacks, strokes and other heart events combined by 17 percent, with moderate confidence. About 56 people would need to do it for about four years to prevent one event, in people without prior heart disease. In the same review there was little or no effect on deaths from any cause or from heart disease. Bigger cuts in saturated fat gave bigger drops in events, which explained most of the differences between studies. Cutting saturated fat is not the same thing as cutting total fat, and mixing them up is how this research gets misreported both ways.
POUNDS LOST put 811 adults on four lower calorie diets for two years, with fat at 20 or 40 percent of calories and protein at 15 or 25 percent. At two years the 20 percent fat groups and the 40 percent fat groups had both lost 3.3 kg. Protein made no difference either, 3.0 against 3.6 kg. Each group session attended went with 0.2 kg more weight loss, and that predicted the result better than the diet mix did.
Hall 2021 fed 20 adults in a hospital unit and let them eat freely. On the low fat plant-based diet they ate 689 fewer calories a day than on the animal-based keto diet over two weeks, a clear difference. That is a big effect, and it is about appetite rather than metabolism. It is the same kind of finding keto produces the other way round when people eat freely.
Hall 2015: 19 adults with obesity lived in an NIH hospital unit and ate the same calories on both diets. Cutting fat led to 89 g of body fat lost per day, against 53 g a day from cutting carbs, a clear difference. This is the cleanest calorie-controlled comparison in the low fat research. It favours low fat, by tens of grams a day.

What happened when people just ate it

The Women's Health Initiative diet trial is the largest test of this diet anyone will ever run, and it is why the low fat era ended. It included 48,835 women past menopause. 40 percent got intensive coaching aimed at 20 percent of calories from fat, with more vegetables, fruit and grains. The other 60 percent were given printed health materials. They were followed for an average of 8.1 years. The coaching worked as a behaviour change: fat intake fell by 8.2 percent of calories by year six, and people ate more vegetables and fruit. The effect on the body was small. LDL fell 3.55 mg/dL, the bottom blood pressure number fell 0.31 mmHg, and a blood clotting factor fell 4.29 percent. There was no real change in HDL, triglycerides, blood sugar or insulin. The health result showed no difference across the board. The risk score for heart disease was 0.97, for stroke 1.02, and for all heart and blood vessel disease 0.98, where one means no difference. Invasive breast cancer, one of the main things the study set out to measure, came in at 0.91, too close to call. Weight did not bounce back, which answered an open question at the time. The coaching group lost 2.2 kg in the first year and was still 0.4 kg lighter at 7.5 years, a clear result. A 2017 analysis found the heart result varied sharply by who people were at the start. In women with no past heart disease and normal blood pressure, the risk score was 0.70. In women with high blood pressure it was 1.04, a clear split. The authors note the heart benefit in the healthy women with normal blood pressure was partly cancelled out by more strokes from blocked arteries. In the 3.4 percent who had heart disease at the start, the heart disease risk score ran at 1.47 during the diet period and 1.61 afterwards. The authors put that down to statin use after the study began muddying the picture. Every one of these is a subgroup picked out after the main result came back empty, and each should be read as a lead to test, not an answer. By 2019, after a typical 19.6 years, the main results still showed no difference, and two secondary signals had appeared: breast cancer followed by death at 0.84, and diabetes needing insulin at 0.87. Look AHEAD is the other large test in people eating on their own. 5,145 adults with type 2 diabetes got a lower calorie, lower fat diet plus exercise. It was stopped at a typical 9.6 years because it was not going to show a benefit. Weight loss was 8.6 against 0.7 percent at one year, and 6.0 against 3.5 percent at the end. The risk score for heart attacks, strokes and heart deaths combined was 0.95, no real difference.

Protein, and whether it muddies the result

Low fat diets are defined by what comes out and say nothing about protein. In practice, the calories taken out of fat get replaced by carbs, not protein. In the Women's Health Initiative, the coaching group ate 8 to 10 percent fewer calories from fat and 8 to 10 percent more from carbs. Where protein was tested directly, it did nothing on its own. In POUNDS LOST, 15 against 25 percent of calories from protein led to 3.0 and 3.6 kg of weight loss at two years, not a real difference. No large low fat study has measured muscle. The Ornish program uses aerobic exercise, not weight training, so the question of muscle has not been asked here at all.

The measured intakes behind the protein figures are on the protein page.

What reliably moves

Measure	Direction	From
Body fat at the same calories	Down, and by more than when cutting carbs	89 g a day against 53 g a day in a hospital research unit with food fixed, a clear difference. It is real, it showed up again in a pooled review of controlled feeding studies, and it is tiny in real terms.
Calories eaten when eating freely	Down sharply compared with keto	689 calories a day less over two weeks in a hospital unit where people tried both diets, a clear difference. This is the diet's strongest single result, and it is about appetite.
LDL (bad) cholesterol	Down, and only slightly when people eat on their own	3.55 mg/dL in the Women's Health Initiative across nearly 49,000 women, with fat cut by 8.2 percent of calories. Bigger drops show up when food is provided and the fat target is strict.
Heart events combined, when saturated fat is cut	Down 17 percent	Across 15 studies and 56,675 people. Bigger cuts in saturated fat gave bigger drops in events. Deaths from any cause and from heart disease showed little or no change.
Heart disease, stroke and breast cancer when total fat is cut	No effect	Risk scores of 0.97, 1.02 and 0.91 over an average 8.1 years in 48,835 women, none clearly different from no effect. Still no difference on the main results at a typical 19.6 years of follow-up.
Body weight against a usual diet	Down	5.41 kg in the pooled studies. Against another real weight loss diet of similar effort, no difference at all.
Triglycerides (blood fats)	Little or no effect, and that matters for who this suits	The Cochrane saturated fat review found little or no effect on triglycerides. In the pooled low fat weight loss studies, higher fat diets won by 1.38 kg exactly in the comparisons where the triglyceride gap at follow-up was at least 0.06 mmol/L. That signals this diet suits a different person than cutting carbs does.

Long term, and serious health events

This diet has the longest and largest trial follow-up of any diet on this site, and the answer it gives is mostly no. The Women's Health Initiative ran the diet for a typical 8.5 years and has followed people for a typical 19.6 years. Its main targets, breast cancer, bowel cancer and heart disease, showed no difference during the diet period or over the whole follow-up. The Ornish evidence sits at the opposite end for size and for how intense the program was, and it has to be reported with both halves. 48 people with moderate to severe heart disease were assigned to a group, and 35 finished five years of artery scans. In the program group, the average narrowing of their arteries fell 1.75 percentage points at one year and 3.1 points at five. In the control group it grew 2.3 points at one year and 11.8 points at five, a clear difference. There were 25 heart events in 28 program patients against 45 in 20 control patients, so the control group's risk was 2.47 times higher. That is a striking result, and it comes with four catches that cannot be skipped. First, the program had five parts, and the diet cannot be separated from the exercise, stress management, quitting smoking and group support. Second, 48 people started and 35 finished. Third, it ran from 1986 to 1992, before today's statins and artery-opening procedures, so the control group then did not fare the way a control group would today. Fourth, the same team's later work, a study of 93 men with early prostate cancer that found PSA down 4 percent against up 6 percent, tested the same package again. It is not a separate confirmation of the diet. Where the evidence from people eating on their own is large, it found nothing. Where it is dramatic, it is small and bundled with other changes.

Sources

Study in people2006
Low-fat dietary pattern and risk of cardiovascular disease: the Women's Health Initiative Randomized Controlled Dietary Modification Trial.
JAMA
48,835 women past menopause were followed for about 8.1 years. The low fat group cut fat by 8.2 percent of calories by year six. LDL (bad) cholesterol fell only 3.55 and the bottom blood pressure number 0.31. Heart disease, stroke and all heart and blood vessel disease came out the same in both groups.
48,835 postmenopausal women, mean 8.1 years. Fat intake fell 8.2 percent of energy by year six. LDL down 3.55 mg/dL, diastolic pressure down 0.31 mmHg. Coronary heart disease HR 0.97 (0.90 to 1.06), stroke 1.02, cardiovascular disease 0.98. All null.
Study in people2006
Low-fat dietary pattern and risk of invasive breast cancer: the Women's Health Initiative Randomized Controlled Dietary Modification Trial.
JAMA
In the same study, the main cancer question was breast cancer. There were 655 cases in the low fat group against 1,072 in the comparison group. Over 8.1 years, the difference was too small to rule out chance.
Same trial, the primary cancer endpoint. 655 cases in the intervention group against 1,072 in the comparison group, hazard ratio 0.91 (95% CI 0.83 to 1.01), not significant over 8.1 years.
Study in people2006
Low-fat dietary pattern and weight change over 7 years: the Women's Health Initiative Dietary Modification Trial.
JAMA
Women in the low fat group lost 2.2 kg in the first year, even though they were not asked to cut calories. They were still 1.9 kg lighter than the comparison group at one year and 0.4 kg lighter at 7.5 years. No subgroup tended to gain weight.
Intervention women lost 2.2 kg in the first year (p < 0.001) and remained lighter than comparison women by 1.9 kg at one year and 0.4 kg at 7.5 years (p = 0.01), with no tendency to weight gain in any subgroup. No calorie restriction goal was set.
Study in people2017
Low-fat dietary pattern and cardiovascular disease: results from the Women's Health Initiative randomized controlled trial.
American Journal of Clinical Nutrition
Overall, heart disease rates did not differ between the groups. Among women with no heart disease and normal blood pressure, low fat was linked to less heart disease, but not among women with high blood pressure. Part of that benefit was offset by more strokes from blocked arteries. These subgroups were picked after a study that found nothing overall.
Incidence of coronary heart disease and total cardiovascular disease did not differ overall. In women without prior cardiovascular disease the coronary hazard ratio was 0.70 (0.56 to 0.87) if normotensive and 1.04 if hypertensive, p for interaction 0.003, with the benefit partially offset by increased ischaemic stroke risk. Post hoc subgroups of a null trial.
Study in people2019
Low-Fat Dietary Pattern among Postmenopausal Women Influences Long-Term Cancer, Cardiovascular Disease, and Diabetes Outcomes.
Journal of Nutrition
This is the long-term overview of the same study. The main results stayed flat, both during the diet years and over later follow-up. Over about 19.6 years, the low fat group had fewer deaths after breast cancer and less diabetes needing insulin.
The long-term overview. Primary outcomes remained null over the intervention period and over cumulative follow-up. Over a median 19.6 years, breast cancer followed by death HR 0.84 (0.74 to 0.96) and diabetes requiring insulin 0.87 (0.77 to 0.98).
Study in people1990
Can lifestyle changes reverse coronary heart disease? The Lifestyle Heart Trial.
The Lancet
This is the original Ornish study. There is no summary on PubMed, so we quote no numbers; the five-year report below has them. The program was a package: a vegetarian diet with 10 percent fat, aerobic exercise, stress management, quitting smoking and group support.
The original Ornish trial. No abstract is indexed in PubMed, so no numbers are quoted from it here; the five-year results in the 1998 report below carry the figures. The intervention was a package of a 10 percent fat vegetarian diet, aerobic exercise, stress management, smoking cessation and group support.
Study in people1998
Intensive lifestyle changes for reversal of coronary heart disease.
JAMA
48 heart patients were put in the program or a control group, and 35 finished five years of artery scans. In the program group, artery narrowing eased by 1.75 points at one year and 3.1 at five; in controls it got worse, by 2.3 and 11.8 points. There were 25 heart events in 28 program patients against 45 in 20 controls. This tested a whole lifestyle package, not just a diet.
48 patients randomised, 35 completed five-year arteriography. Percent diameter stenosis fell 1.75 points at one year and 3.1 at five in the experimental group; it rose 2.3 and 11.8 points in controls, p = 0.001. Cardiac events 25 in 28 experimental patients against 45 in 20 controls, control risk ratio 2.47 (1.48 to 4.20). A five-component lifestyle package, not a diet trial.
Study in people2005
Intensive lifestyle changes may affect the progression of prostate cancer.
Journal of Urology
93 men with early prostate cancer who had turned down standard treatment got the same lifestyle package or usual care for one year. PSA fell 4 percent in the program group and rose 6 percent in the others. In a dish, their blood slowed the growth of prostate cancer cells by 70 percent against 9 percent. Again, this was a package, not just a diet.
93 men with early prostate cancer who had declined conventional treatment, randomised to the same lifestyle package or usual care for one year. PSA fell 4 percent against a 6 percent rise (p = 0.016) and serum-stimulated LNCaP cell growth was inhibited 70 percent against 9 percent (p < 0.001). Again a package, not a diet.
Review of studies2015
Effect of low-fat diet interventions versus other diet interventions on long-term weight change in adults: a systematic review and meta-analysis.
Lancet Diabetes and Endocrinology
A review pooled 53 studies with 68,128 people, each lasting at least one year. Low carb beat low fat by 1.15 kg. Low fat did no better than other higher fat weight loss diets, but beat a usual diet by 5.41 kg. How good low fat looks depends on how much effort went into the comparison group.
53 trials, 68,128 participants, at least one year. Low carbohydrate beat low fat by 1.15 kg (0.52 to 1.79). Low fat did not differ from other higher-fat weight loss interventions (0.36 kg, minus 0.66 to 1.37). Low fat beat a usual diet by 5.41 kg. The apparent effect depends on the intensity of the comparison group's intervention.
Review of studies2020
Reduction in saturated fat intake for cardiovascular disease.
Cochrane Database of Systematic Reviews
A review pooled 15 studies with 56,675 people. Cutting saturated fat lowered heart and blood vessel events by 17 percent; in people without heart disease, 56 had to make the change to prevent one event. It made little or no difference to deaths from any cause or from heart disease. The more saturated fat was cut, the bigger the drop in events.
15 randomised trials, 56,675 participants. Reducing saturated fat cut combined cardiovascular events 17 percent (RR 0.83, 0.70 to 0.98, moderate certainty), number needed to treat 56 in primary prevention. Little or no effect on all-cause mortality (0.96) or cardiovascular mortality (0.95). Greater saturated fat reduction produced greater event reduction.
Study in people2013
Cardiovascular effects of intensive lifestyle intervention in type 2 diabetes.
New England Journal of Medicine
5,145 adults with type 2 diabetes ate a lower calorie, lower fat diet and got more active, or were in a comparison group. They lost 8.6 percent of body weight against 0.7 percent at one year, and 6.0 against 3.5 percent at the end. Heart and stroke events did not drop, and the study was stopped at about 9.6 years because it was not going to show a benefit.
Look AHEAD. 5,145 adults with type 2 diabetes on a calorie-reduced lower fat diet plus activity, stopped for futility at median 9.6 years. Weight loss 8.6 against 0.7 percent at one year and 6.0 against 3.5 percent at the end. Cardiovascular composite HR 0.95 (0.83 to 1.09), p = 0.51.
Study in people2009
Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates.
New England Journal of Medicine
811 adults followed one of four lower calorie diets for two years. Weight loss was about the same whatever the mix: 3.3 kg on both 20 and 40 percent fat, 3.0 and 3.6 kg on 15 and 25 percent protein, and 2.9 and 3.4 kg on 65 and 35 percent carbs. Going to more group sessions predicted more weight loss, about 0.2 kg per session.
POUNDS LOST. 811 adults, four calorie-reduced diets, two years. 20 percent fat and 40 percent fat arms both lost 3.3 kg; 15 percent and 25 percent protein arms lost 3.0 and 3.6 kg; 65 percent and 35 percent carbohydrate arms 2.9 and 3.4 kg, all p > 0.20. Session attendance predicted weight loss at 0.2 kg per session.
Study in people2015
Calorie for Calorie, Dietary Fat Restriction Results in More Body Fat Loss than Carbohydrate Restriction in People with Obesity.
Cell Metabolism
19 adults with obesity lived on an NIH hospital ward and tried both diets at the same calories. Cutting fat led to 89 grams of body fat lost a day, against 53 grams when cutting carbs, a clear difference. This is the cleanest test with calories held equal, and the gap is only tens of grams.
NIH metabolic ward, 19 adults, isocaloric, each participant on both diets. Fat restriction produced 89 g/day of body fat loss against 53 g/day on carbohydrate restriction, p = 0.002. The cleanest calorie-controlled comparison, and the effect size is tens of grams.
Study in people2021
Effect of a plant-based, low-fat diet versus an animal-based, ketogenic diet on ad libitum energy intake.
Nature Medicine
20 adults lived on a hospital ward, tried both diets, and ate as much as they wanted. Over two weeks, they ate 689 fewer calories a day on the low fat plant-based diet, a clear gap. This is a result about appetite, on a hospital ward, over just two weeks.
20 adults, inpatient, ad libitum crossover. The low fat plant-based diet led to 689 kcal/day less energy intake over two weeks, p < 0.0001. An appetite result, in a ward, over two weeks.

What people report

These are things people say about their own eating. Nobody checked them, so they are not evidence. They are here because they tell you what to expect and what to watch for, which the studies do not. They cannot tell you whether anything works.

A lot of food for the calories, described as the main reason it feels doable long term. That fits the 689 calories a day difference measured in a hospital unit.
Strong early weight loss, then a plateau. That matches the study data exactly: 2.2 kg in year one and 0.4 kg of difference left at 7.5 years.
Hunger coming back once the novelty of the new food wears off. This is reported often, and in self-report it cannot be told apart from ordinary drift off a diet.
No change in cholesterol, reported by a sizeable minority. That fits the average LDL drop of 3.55 mg/dL in the largest trial.
Gut complaints and gas as fibre goes up, usually said to settle within weeks.
Trouble feeling full and cooking without fat, and trouble eating out: the two most cited practical reasons for stopping.
A vocal community around the Ornish and whole-food plant-based versions reports chest pain from heart disease going away and needing less medicine. That is what the study reported in 28 people, and the study cannot credit it to the diet alone.

Sources: Whole-food plant-based and Ornish program communities, general weight loss forums, and how well people stuck to the diet in the studies. For the Women's Health Initiative that is unusually well recorded, because intake was measured again and again across eight years. Otherwise unchecked self-report.

Who this is wrong for

Anyone reading the Ornish artery scan result as a diet result. Five things changed at once in 48 people, 35 of whom finished, in a comparison from before statins. The package produced the result. Which part did it has never been measured.
Anyone whose cholesterol problem is high triglycerides with low HDL. At steady weight this diet did little or nothing for triglycerides. In the pooled studies, the higher fat diets won by more exactly where the triglyceride gap was widest.
Anyone expecting cutting fat to do the work by itself. Against another real diet of similar effort there is no weight difference. In the largest trial ever run, the difference from the comparison group at 7.5 years was 0.4 kg.
Anyone who takes the Women's Health Initiative subgroups as advice. The heart risk score of 0.70 in healthy women with normal blood pressure, and the scores above 1 in women with past heart disease, were both picked out after the main result came back empty. The authors put the second down to statin use muddying the picture.
Anyone mixing up cutting total fat with cutting saturated fat. The saturated fat studies cut heart attacks, strokes and other heart events combined by 17 percent. The total fat study did not cut them at all.
Anyone trying a 10 percent fat diet without support. The only studies that reached and held it gave intensive group sessions. The study aiming at 20 percent, with intensive coaching, got fat down by 8.2 percent of calories across eight years.

Questions

Didn't the low fat diet fail?: The largest test of it did. 48,835 women past menopause were assigned for an average of 8.1 years. Heart disease, stroke, all heart and blood vessel disease, and invasive breast cancer all showed no difference, and LDL fell only 3.55 mg/dL. What it did not do is cause harm or weight gain, which was an open question at the time. And a different approach, cutting saturated fat rather than total fat, did cut heart attacks, strokes and other heart events combined by 17 percent across 15 studies.
But at the same calories, is low fat better than low carb?: For body fat loss, yes, by an amount too small to plan around. In a hospital research unit with food fixed, cutting fat led to 89 g a day of body fat loss, against 53 g a day from cutting carbs. That is a real difference of about 36 grams of fat a day. It is also the opposite of what the carbohydrate-insulin model predicts, which is why it gets quoted so often.
What about the Ornish reversal trial?: It is real, and it is not a diet trial. 48 people were assigned to a package: a 10 percent fat vegetarian diet plus aerobic exercise, stress management, quitting smoking and group support. 35 finished five years of artery scans. Artery narrowing eased in the program group and got much worse in the control group, and the program group had roughly half the rate of heart events. Which of the five parts did that has never been measured. The study was small, and it ran from 1986 to 1992, before today's statins and artery-opening procedures.
Will I lose weight on it?: Against doing nothing, yes, about 5.4 kg in the pooled studies. Against another real weight loss diet of similar effort, no difference at all, and a low carb diet beats it by 1.15 kg. In the four-group study that set fat at 20 to 40 percent of calories with calories matched, both groups lost 3.3 kg at two years. How many group sessions people went to predicted the result better than the diet mix did.
Who does this pattern suit least?: People whose cholesterol problem is high triglycerides with low HDL. At steady weight this diet did little or nothing for triglycerides. In the pooled studies, the higher fat diets won by the most exactly where the triglyceride gap at follow-up was widest. That is the clearest sign anywhere in this section that low fat and low carb suit different people.