Fett in der Ernährung wurde gefürchtet, verteidigt und dann wieder gefürchtet; die Verwirrung entsteht dadurch, dass man Studien einzeln liest. Hier ist der aktuelle Stand der Evidenz. Gesättigtes Fett für sich genommen steht dem Herz-Kreislauf-Risiko näher an neutral als sein Ruf es vermuten lässt, und eine Reduktion des Fettes machte Menschen nicht schlanker.
Entscheidend ist, was den Platz des Fettes einnimmt: Ersetzt man gesättigtes Fett durch mehrfach ungesättigte Fettsäuren aus pflanzlichen Ölen, Nüssen und Meeresfrüchten, sinkt die Rate der Herzinfarkte um etwa ein Fünftel; ersetzt man es durch raffinierte Stärke und Zucker, geschieht dies nicht. Zwei Punkte stehen fest: Industriell hergestelltes Transfett erhöht das Risiko für Herz-Kreislauf-Erkrankungen eindeutig, und gesättigtes Fett erhöht das LDL-Cholesterin stärker als jede andere Fettsäure. Fette aus ganzen Lebensmitteln wie Butter und Eiern sind nahezu neutral, und das stärkste Signal über alle Befunde hinweg weist in Richtung weniger verarbeiteter Lebensmittel, unabhängig von der Zahl auf dem Etikett.
Findings & Outcomes
What This Is
Dietary fat is the fat in food: the saturated fat in butter, the unsaturated fat in oils, nuts and fish, and the industrial trans fat in some processed food. Four questions get tangled together, and the evidence answers them differently. Does saturated fat on its own cause heart disease? Does eating fat put on weight? Which fat clearly harms? And what should take the place of the fat you cut? The relevant evidence runs from 1960s policy trials to cohort pools published after 2010.
How The Low-Fat Era Began
The low-fat era grew from a chain of reasoning: saturated fat raises cholesterol, and cholesterol relates to heart disease. The logic was promoted with more certainty than the trials of the 1960s could carry. It became policy across the 1970s and 1980s, and packaged food was reformulated to match. Fat came out of products, and sugar and refined starch went in to keep them palatable.
The result ran the wrong way for the theory. Fat intake fell steadily from 1970 onward while sugar consumption and obesity climbed. Coincidence in time does not prove cause, but it is a poor showing for the idea that fat was the problem.
Part of that consensus was bought. A historical analysis of internal industry documents found that in the 1960s a sugar trade group paid Harvard researchers to publish a favorable review (Kearns 2016). The review played down sugar's role in heart disease and pointed attention toward fat and cholesterol, with the funding undisclosed. That single episode did not create the low-fat consensus. It shows the sugar industry helping steer blame onto fat before the science had settled, one reason some older literature reads as slanted. The wider pattern is the subject of how industry shapes science.
Saturated Fat On Its Own
Ask whether saturated fat by itself causes heart disease and the cohort data say roughly no. A meta-analysis of 21 cohorts covering almost 350,000 people found no significant association between saturated fat intake and coronary heart disease, stroke, or cardiovascular disease overall (Siri-Tarino 2010). One caution belongs on it: the work was funded by the National Dairy Council, an industry tie that earns the same skepticism as the sugar money behind the low-fat literature. The finding held up in independent work.
Two later reviews point the same way. A systematic review in the BMJ reached the same conclusion for saturated fat and death, heart disease and type 2 diabetes, while flagging trans fat as harmful (de Souza 2015). The PURE study, following 135,335 people across 18 countries, found higher total fat intake tracking with lower mortality and higher carbohydrate intake with higher mortality (Dehghan 2017).
Why LDL Still Matters
Saturated fat is not inert. It lifts LDL cholesterol further than any other fat, established across 60 controlled feeding trials (Mensink 2003). A flat cohort result is no invitation to eat it without limit. Both hold once you know what LDL measures. It is a stand-in for heart disease, a marker that tracks the risk without being the disease. The same food that raises LDL also raises HDL, so its net effect on heart attacks depends on what replaces it. That is why the cohort outcomes and the cholesterol number can point in different directions at once. The lipid detail sits in Cholesterol and lipids.
What You Put In Its Place
In randomized trials where polyunsaturated fat from oils, nuts and oily fish replaced saturated fat, coronary events fell about 19% (Mozaffarian 2010). That is the strongest signal in the whole literature, and it turns on what you swap in. The Cochrane review put cardiovascular events down 21%, with the benefit concentrated where polyunsaturated fat did the replacing (Hooper 2020). What replaces the fat sets the outcome; the amount you eat matters far less.
The Cochrane review put cardiovascular events down 21%, with the benefit concentrated where polyunsaturated fat did the replacing (Hooper 2020). What replaces the fat sets the outcome; the amount you eat matters far less.
The replacement has to be the right one. A pooled analysis of 11 cohorts found that replacing saturated fat with polyunsaturated fat lowered coronary risk, while replacing it with carbohydrate raised risk slightly (Jakobsen 2009). Fat out, refined starch and sugar in, was the swap the low-fat era encouraged, and it was the wrong one. The Mediterranean diet is that same swap made into a whole way of eating: olive oil, nuts, fish and vegetables. It has the longest outcome record of any whole-diet pattern.
Does Eating Fat Make You Fat
Gram for gram, fat is energy-dense, at nine calories a gram (9 kcal/g) against four (4 kcal/g) for carbohydrate and protein. That did not translate into weight loss when the low-fat diet was tested head-on.
The Women's Health Initiative randomized nearly 49,000 postmenopausal women to a low-fat pattern and followed them about 7.5 years. Their weight ended up only about 0.9 lb (0.4 kg) below the comparison group, too small a difference to matter (Howard 2006).
The DIETFITS trial pushed the point further. It put 609 adults on either a healthy low-fat or a healthy low-carbohydrate diet for a year. They lost almost the same amount: about 11.7 lb (5.3 kg) against 13.2 lb (6.0 kg). Neither genes nor insulin levels predicted who did better on which (Gardner 2018). Both groups cut refined starch and sugar and leaned on whole food, the shared ingredient the researchers pointed to. Total calories and the quality of what you eat drive body weight; the fat fraction does far less than the low-fat message claimed.
What About Butter
A systematic review of butter across more than 630,000 people found it essentially neutral for cardiovascular disease and stroke (Pimpin 2016). Overall mortality rose slightly, and the risk of type 2 diabetes came out slightly lower. Neutral is not the same as beneficial. These are observational comparisons against whatever else people happened to eat. Butter looks neutral partly because the foods it was compared with, usually bread and refined starch, are no better. So butter comes out neutral, its old reputation as a hazard unsupported by the evidence.
Trans Fat: The One Clear Harm
Industrial trans fat, made by partially hydrogenating vegetable oil to keep it solid and shelf-stable, is the one fat the outcome data clearly tie to harm. The BMJ review linked it to higher coronary heart disease and death from it (de Souza 2015). The long-standing estimate is that each 2% of calories from trans fat raises coronary risk about 23% (Mozaffarian 2006). It raises LDL, lowers HDL, and promotes inflammation, so three mechanisms push the same way.
Denmark proved that with policy. In 2003 it became the first country in the world to cap industrial trans fat at 2% of fats, and the European Union and WHO later followed. Danish researchers sampling supermarket foods across Europe found industrial trans fat still present years later wherever no such limit applied (Stender 2016).
Seed Oils
Vegetable and seed oils, a 20th-century staple of the industrial food supply, are the main source of the polyunsaturated fat that carried the substitution benefit against saturated fat. There is no trial evidence of harm from these oils at ordinary dietary amounts. The reasonable caution is the fried fast food and packaged snacks that seed oils usually come with, so the food matters more than the oil.
The Evidence, Graded
The Research & Studies
Everything here is based on the research we have collected and checked, sorted into groups and ordered with the strongest evidence first. Click any claim to open the studies behind it.
Cholesterol And Lipids
Replacing saturated fat with polyunsaturated fat cut coronary events about 19%
In randomized trials, swapping saturated fat for polyunsaturated fat (from vegetable oils, nuts and seafood) lowered heart attacks and cardiovascular events by roughly a fifth.
Mozaffarian and colleagues pooled 8 randomized controlled trials (about 13,614 participants, 1,042 coronary events) in which polyunsaturated fat was increased in place of saturated fat, finding a 19% reduction in coronary heart disease events (RR 0.81, 95% CI 0.70 to 0.95), equivalent to about a 10% lower risk per 5% of energy substituted. Hooper and colleagues' 2020 Cochrane review of trials that reduced saturated fat found a 21% reduction in cardiovascular events (RR 0.79, 95% CI 0.66 to 0.93); its subgroup analysis did not find a significant difference between replacing saturated fat with polyunsaturated fat or with carbohydrate, attributing the benefit to the degree of saturated-fat and serum-cholesterol reduction.
The studies · 2
Mozaffarian et al., effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials · PLoS Med 2010;7(3):e1000252
Hooper et al., reduction in saturated fat intake for cardiovascular disease (Cochrane review) · Cochrane Database Syst Rev 2020;(5):CD011737
Dietary cholesterol raised LDL only about 7 mg/dL and was not clearly tied to heart disease
For most people, the cholesterol in food such as eggs has only a small effect on blood cholesterol and is not clearly tied to heart disease.
Berger and colleagues systematically reviewed 40 studies (17 cohort studies, reported across 19 publications) on dietary cholesterol. Dietary cholesterol was not statistically significantly associated with coronary heart disease or with ischemic or hemorrhagic stroke, and it produced a small but statistically significant average rise in serum total (about 11 mg/dL) and LDL (about 7 mg/dL) cholesterol, with the LDL rise attenuating at very high intakes. The authors rated the overall evidence as low quality, meaning the true effect could still differ from the summary. This is why blanket egg limits were relaxed in later dietary guidance.
The study · 1
Berger et al., dietary cholesterol and cardiovascular disease: a systematic review and meta-analysis · Am J Clin Nutr 2015;102(2):276-94
How it works
Saturated fat raised LDL more than any other fat, across 60 feeding trials
Saturated fat does raise LDL cholesterol, more than other fats do, though it also raises HDL, so the full blood-lipid picture is mixed.
Mensink and colleagues meta-analyzed 60 controlled feeding trials of the effect of dietary fats and carbohydrates on blood lipids. Isocaloric replacement of carbohydrate with saturated fat raised LDL cholesterol, and saturated fat raised LDL more than monounsaturated or polyunsaturated fat did. The same replacement raised HDL cholesterol and lowered fasting triglycerides, while leaving the total-to-HDL ratio essentially unchanged; only cis-unsaturated fats lower that ratio. LDL is a biomarker and an established risk factor, but it is a surrogate: the same food can nudge LDL up while its effect on heart attacks depends on what it replaces, which is why the biomarker and hard-outcome literatures can point different ways.
The study · 1
Mensink et al., effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids: a meta-analysis of 60 controlled trials · Am J Clin Nutr 2003;77(5):1146-55
Heart And Vascular
Each 2% of calories from industrial trans fat raised coronary risk about 23%
Industrial trans fat clearly raises the risk of heart disease, more strongly than any other fat.
De Souza and colleagues' 2015 systematic review of observational studies found trans fat intake associated with higher all-cause mortality (relative risk 1.34), coronary heart disease mortality (1.28) and coronary heart disease (1.21). Mozaffarian and colleagues' earlier synthesis estimated that each 2% of energy from trans fat raises coronary heart disease risk by about 23%, driven by trans fat raising LDL, lowering HDL, and promoting inflammation and endothelial dysfunction. This is the one dietary fat where the case for harm is strong and consistent, and it is why industrial trans fat has been removed from the food supply in many countries.
The studies · 2
de Souza et al., intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes · BMJ 2015;351:h3978
Mozaffarian et al., trans fatty acids and cardiovascular disease · N Engl J Med 2006;354(15):1601-13
Saturated fat by itself was not linked to more heart disease across 347,747 people
Pooling 21 long-term studies of almost 350,000 people, eating more saturated fat by itself was not linked to more heart disease or stroke.
Siri-Tarino and colleagues pooled 21 prospective cohort studies covering 347,747 subjects with 5 to 23 years of follow-up. The relative risk of coronary heart disease for the highest versus lowest saturated fat intake was 1.07 (95% CI 0.96 to 1.19), for stroke 0.81 (0.62 to 1.05), and for cardiovascular disease overall 1.00 (0.89 to 1.11), none statistically significant. The result says nothing about what people ate instead of saturated fat, which is the question the substitution analyzes answer.
The study · 1
Siri-Tarino et al., meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease · Am J Clin Nutr 2010;91(3):535-46
Replacing saturated fat with carbohydrate slightly raised coronary risk (hazard ratio 1.07)
Trading saturated fat for polyunsaturated fat lowered heart disease, but trading it for carbohydrate did not help and nudged risk slightly upward.
Jakobsen and colleagues pooled 11 prospective cohorts (344,696 people, 5,249 coronary events over 4 to 10 years). Replacing 5% of energy from saturated fat with polyunsaturated fat was associated with a hazard ratio of 0.87 for coronary events and 0.74 for coronary death. Replacing the same 5% with carbohydrate was associated with a hazard ratio of 1.07 (95% CI 1.01 to 1.14) for events, and monounsaturated-fat replacement showed no clear benefit. This is the substitution the low-fat era encouraged, and it was the wrong swap.
The study · 1
Jakobsen et al., major types of dietary fat and risk of coronary heart disease: a pooled analysis of 11 cohort studies · Am J Clin Nutr 2009;89(5):1425-32
Butter looked roughly neutral for heart disease across 636,151 people
Butter came out roughly neutral for heart disease and stroke, with a tiny bump in overall mortality and a slightly lower diabetes risk.
Pimpin and colleagues systematically reviewed 9 cohort studies covering 636,151 participants and 6.5 million person-years. Per 14 g/day of butter, the relative risk was 1.01 for total mortality, 1.00 for cardiovascular disease, 1.00 for stroke and 0.96 for type 2 diabetes. The authors concluded butter is relatively neutral for cardiovascular and mortality outcomes and possibly slightly protective against diabetes, and cautioned that the comparison foods matter: butter against refined carbohydrate looks different from butter against olive oil.
The study · 1
Pimpin et al., is butter back? A systematic review and meta-analysis of butter consumption and risk of cardiovascular disease, diabetes, and total mortality · PLoS One 2016;11(6):e0158118
Longevity And Mortality
Highest total-fat intake tracked with 23% lower death risk across 18 countries (PURE)
In a large 18-country study, people eating the most total fat had a lower risk of dying over the follow-up, and people eating the most carbohydrate had a higher risk.
The PURE study (Dehghan et al.) followed 135,335 people aged 35 to 70 across 18 countries for a median 7.4 years. Comparing the highest with the lowest quintile, total fat carried a hazard ratio of 0.77 for total mortality, saturated fat 0.86, monounsaturated 0.81 and polyunsaturated 0.80; higher carbohydrate intake carried a hazard ratio of 1.28. Total fat and each fat type were not associated with myocardial infarction or cardiovascular death, and saturated fat was associated with lower stroke risk. The signal is strongest at the extremes of carbohydrate intake seen in low-income countries.
The study · 1
Dehghan et al., associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries (PURE) · Lancet 2017;390(10107):2050-2062
Death risk was lowest at 50 to 55% of calories from carbohydrate, higher at both extremes
Both very low-carb and very high-carb diets tracked with a shorter life; what mattered at the low-carb end was whether the fat and protein came from animals or plants.
Seidelmann and colleagues followed 15,428 adults in the ARIC cohort for a median 25 years and pooled the finding with studies totalling 432,179 people. The relationship between carbohydrate intake and mortality was U-shaped, with the lowest risk at 50 to 55% of energy from carbohydrate. Below 40% and above 70% both carried higher mortality. Among low-carbohydrate eaters, replacing carbohydrate with animal-derived fat and protein carried a hazard ratio of 1.18, while replacing it with plant-derived fat and protein carried 0.82. This is the nuance that keeps the page from tipping into fat-is-free.
The study · 1
Seidelmann et al., dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis · Lancet Public Health 2018;3(9):e419-e428
Weight And Fat Loss
A low-fat diet left nearly 49,000 women about 0.9 lb (0.4 kg) lighter after 7.5 years
Almost 49,000 women were asked to eat low-fat for years; their weight ended up essentially the same as the group who were not.
The Women's Health Initiative Dietary Modification Trial (Howard et al.) randomized 48,835 postmenopausal women to a low-fat eating pattern (target 20% of energy from fat, more fruit, vegetables and grains) or usual diet. The intervention group lost about 4.9 lb (2.2 kg) in the first year, but the difference from the comparison group narrowed to roughly 0.9 lb (0.4 kg) by year 7.5. There was a modest tendency for weight change to track the actual reduction in fat achieved, but cutting dietary fat did not produce meaningful lasting weight loss.
Who this may not transfer to:Measured entirely in postmenopausal women. Whether a low-fat pattern does more or less for weight in men or younger women was not tested here, though the head-to-head diet trials that did enrol both sexes point the same way.
The study · 1
Howard et al., low-fat dietary pattern and weight change over 7 years: the Women's Health Initiative Dietary Modification Trial · JAMA 2006;295(1):39-49
Healthy low-fat and low-carb diets lost about the same, 11.7 lb (5.3 kg) versus 13.2 lb (6.0 kg) in a year
When people ate either a healthy low-fat or a healthy low-carb diet for a year, both groups lost about the same amount of weight.
The DIETFITS trial (Gardner et al.) randomized 609 overweight adults to a healthy low-fat or healthy low-carbohydrate diet, both emphasizing vegetables and minimally processed whole foods with no calorie target, for 12 months. Mean weight loss was 11.7 lb (5.3 kg) on low-fat and 13.2 lb (6.0 kg) on low-carbohydrate, a non-significant difference. Pre-specified analyzes found that neither a genotype pattern nor baseline insulin secretion identified who would succeed on which diet. Both groups were coached toward whole foods, which the authors highlighted as the shared ingredient.
The study · 1
Gardner et al., effect of low-fat vs low-carbohydrate diet on 12-month weight loss: the DIETFITS randomized clinical trial · JAMA 2018;319(7):667-679
Go Deeper
- The Mediterranean diet, the whole-diet trials behind the substitution finding.
- How industry shapes science, for the funding and framing behind the low-fat consensus.
- Whole foods, the pattern the evidence most consistently supports.
- Cholesterol and lipids, for what LDL and HDL actually predict.
- Type 2 diabetes, the metabolic outcome behind much of the fat-versus-carbohydrate question.
- Seed oils, for the evidence on the oils that carry most dietary polyunsaturated fat.
The Chinese Medicine View
Common Questions
Are eggs and dietary cholesterol a problem?
For most people the cholesterol in food has only a small effect on blood cholesterol and is not clearly tied to heart disease (Berger 2015). An egg-rich diet raises LDL by about 7 mg/dL on average, a small and inconsistent shift. A minority, the so-called hyper-responders, move further. Hyper-responders aside, dietary cholesterol moves blood LDL little, and the egg question is largely settled.
Should I just cut carbohydrates instead?
Not to an extreme. When carbohydrate intake was tracked against mortality the relationship was U-shaped, with the lowest risk around a moderate intake (Seidelmann 2018). Both very low and very high intakes carried higher risk. At the low-carbohydrate end it mattered a great deal whether the fat and protein replacing the carbohydrate came from animals or plants. What replaced the carbohydrate shaped the risk far more than how much was cut.
Do the natural trans fats in meat and dairy carry the same risk?
At ordinary intakes, no. Naturally occurring trans fats, present in small amounts in dairy and meat, do not carry the same signal that the industrial kind does. The concern is the manufactured trans fat of the 20th century, sold mostly through fried fast food, packaged baked goods and older margarines.
Explore Related
Other pages this one connects to, by the evidence they share, the outcomes they touch, and the ground they cover.
All 13 sources on this page independently checked and cross-referenced.
Thomas Dehli, Founder & Editor, Sacred Lotus
Sacred Lotus has published Chinese medicine reference material since 2001. Integrative pages are held to the same standard as the herb and formula library: cite the source, grade the claim at its real strength, and say where the research has not looked. This page is educational and it is not medical advice. Last reviewed and updated August 10, 2026.
Evidence strength
How confidently the research supports a claim. Strength describes the evidence, not our endorsement.