Browse the evidence

The association between weight gain and breast cancer risk is stronger in women who have never used postmenopausal hormones (PMH) compared to those who have ever used PMH.

For postmenopausal women who have never used hormone therapy, weight gain poses a significantly higher breast cancer risk than for those who have used it. This is because exogenous hormones mask the hormonal effects of body fat.

The risk of cardiovascular disease (myocardial infarction and stroke) is significantly elevated during the prediabetic phase, starting at least 15 years before the clinical diagnosis of type 2 diabetes.

If you have risk factors for diabetes (such as high blood pressure, high cholesterol, or family history), your cardiovascular risk is already elevated, even if you haven't been diagnosed with diabetes yet. Do not wait for a diabetes diagnosis to aggressively manage blood pressure, cholesterol, and lifestyle factors, as the 'clock' for heart disease starts ticking years in advance.

Type 2 diabetes mellitus in women is associated with a dramatically increased risk of fatal coronary heart disease (CHD) and all-cause mortality, with risk levels comparable to or exceeding those of women with prior CHD but no diabetes.

If you are a woman with type 2 diabetes, your risk of dying from heart disease is extremely high—comparable to a man with diabetes or a woman who has already had a heart attack. You must treat your cardiovascular risk factors (blood pressure, cholesterol, smoking) with the same aggression as someone who has already had cardiac events. Do not assume you are 'low risk' because you haven't had symptoms yet.

The duration of clinical diabetes is monotonically associated with increased risk of fatal CHD, with risk exceeding that of prior CHD alone after 15 years of diabetes duration.

If you have had diabetes for more than 15 years, your risk of fatal heart disease is extremely high, potentially triple that of someone with a prior heart attack if you also have prior CHD. You need aggressive cardiovascular risk management (lipids, BP, lifestyle) regardless of how well you feel. Do not let the passage of time normalize your risk.

Sustained caloric restriction significantly lowers circulating Triiodothyronine (T3) and Thyroid-Stimulating Hormone (TSH) levels, mirroring adaptations seen in long-lived animal models.

Caloric restriction lowers thyroid hormone levels (T3 and TSH) within the normal range. This is a known adaptation to energy deficit and is associated with longevity in animal studies, though its direct causal link to human lifespan is not yet established.

Acute resistance exercise-induced elevations in endogenous anabolic hormones (testosterone, GH, IGF-1) do not enhance training-induced muscle hypertrophy or strength gains.

You do not need to perform high-volume, short-rest resistance training specifically to 'spike' your testosterone or growth hormone to build muscle. Standard resistance training protocols that focus on mechanical tension and progressive overload are sufficient for hypertrophy and strength gains, regardless of the acute hormonal response. Do not sacrifice recovery or technique in pursuit of a 'pump' or hormonal spike.

Obesity is a risk factor for the incidence of several cancers including endometrial, colorectal, kidney, esophagus, postmenopausal breast, and pancreas.

Maintaining a healthy weight is crucial for preventing several common cancers, including breast (postmenopausal), colorectal, kidney, esophagus, pancreas, and endometrial cancers.

Obesity involves the biological defense of an elevated body fat mass set point, driven by homeostatic mechanisms that resist fat loss through increased hunger and metabolic efficiency.

Understand that your body actively fights against fat loss through biological mechanisms like increased hunger and reduced metabolic rate. This is not a failure of willpower but a physiological response. Effective treatment requires strategies that address these biological defenses, not just caloric restriction.

Roux-en-Y gastric bypass (RYGB) surgery effectively reduces the defended level of body fat mass by altering gut-brain communication, increasing anorexigenic gut peptides, and reducing food reward valuation.

For morbid obesity, Roux-en-Y gastric bypass is the most effective treatment, significantly reducing the body's defended fat mass set point. It works by altering gut hormones and reducing food reward, leading to sustained weight loss.

Physiological adaptations to weight loss, including slowed resting metabolic rate (RMR) and increased hunger hormones, actively defend a higher body weight 'set-point' and promote weight regain.

After you lose weight, your body will fight to get it back by slowing your metabolism and increasing hunger. This is a biological 'set-point' defense, not a lack of willpower. To maintain weight loss, you must accept that you will need to be more vigilant about food intake and exercise than before, as your body is biologically programmed to regain the weight.

Long-term calorie restriction in nonobese adults increases Sex Hormone-Binding Globulin (SHBG) levels in men, while free testosterone levels decrease significantly at 12 months but not at 24 months.

For men, long-term calorie restriction significantly raises SHBG, which is associated with better metabolic health. While free testosterone drops temporarily at 12 months, it returns to levels comparable to controls by 24 months, suggesting the reproductive axis is not permanently suppressed.

Two-year caloric restriction (approx. 25% reduction) in non-obese younger adults causes significant bone mineral density (BMD) loss at osteoporotic fracture sites (lumbar spine, total hip, femoral neck) driven by uncoupled bone turnover (increased resorption, decreased formation).

If you are undertaking long-term caloric restriction for longevity, be aware that it can cause measurable bone loss at the spine and hip, even if you are young and non-obese. This loss is driven by hormonal changes and increased bone turnover. To mitigate this, ensure adequate calcium and Vitamin D intake (as done in this study) and consider resistance training to preserve fat-free mass, which was identified as a key factor in protecting hip BMD.

Long-term calorie restriction (25% reduction for 2 years) in nonobese humans does not reduce serum IGF-1 levels, but significantly increases IGFBP-1 and decreases the IGF-1:IGFBP-1 ratio, thereby reducing bioavailable IGF-1.

If you are practicing long-term calorie restriction to optimize longevity markers, do not expect your total IGF-1 levels to drop significantly unless you also restrict protein. Instead, you will see a beneficial reduction in bioavailable (free) IGF-1 due to increased IGFBP-1. This suggests that the mechanism of action for CR in humans may differ from rodents, relying more on binding proteins than total hormone suppression.

Long-term calorie restriction in nonobese humans does not produce a sustained increase in serum cortisol, unlike the sustained increase seen in rodents.

Do not worry that long-term calorie restriction will keep your cortisol chronically high. In nonobese individuals, any increase in cortisol is mild and transient, disappearing after the first year. This contrasts with rodent studies where cortisol increases are sustained.

Intensive glucose control (targeting HbA1c <6.0-6.5%) in Type 2 Diabetes does not significantly reduce cardiovascular events and may increase mortality, whereas intensive control in Type 1 Diabetes shows a sustained legacy benefit on CV outcomes.

Do not assume that achieving very low HbA1c levels (e.g., <6.0%) will prevent heart attacks in Type 2 Diabetes. In fact, aggressive control can be dangerous. Prioritize blood pressure and cholesterol management for cardiovascular protection.

The carbohydrate-insulin model, which posits that high carbohydrate intake causes hyperinsulinemia leading to fat storage and weight gain, is experimentally falsified because low-carbohydrate diets fail to produce the expected fat loss or sustained increase in energy expenditure.

Do not rely on the carbohydrate-insulin model to explain weight loss. Low-carb diets do not inherently increase energy expenditure or fat loss compared to other diets when calories are matched. Focus on sustainable dietary patterns.

Bariatric surgery (specifically Roux-en-Y gastric bypass) is the only current obesity treatment effective for long-term weight loss and resolution of comorbidities, whereas non-surgical lifestyle and pharmacological interventions typically produce modest, poorly sustained weight loss.

If you have severe obesity, lifestyle changes and current medications rarely lead to lasting weight loss. Bariatric surgery is currently the only intervention proven to sustain significant weight loss and resolve related health issues long-term. Discuss surgical options with a specialist if you qualify, as non-surgical methods often fail to maintain results.

Metabolic surgery reduces the risk of microvascular and macrovascular complications, as well as all-cause mortality, compared to non-surgical treatment in T2D patients.

Beyond weight loss, metabolic surgery significantly lowers the risk of diabetes-related organ damage (eyes, kidneys, nerves) and reduces the risk of early death compared to managing diabetes with medication and lifestyle changes alone.

Leptin regulates glucose homeostasis through direct actions on POMC neurons, but does not regulate food intake or energy balance through direct actions on these same neurons.

Understanding that leptin's effect on blood sugar is distinct from its effect on hunger helps explain why leptin therapy fails for weight loss in most obese individuals (who are leptin resistant) but might still have metabolic benefits. It shifts focus from 'blocking hunger' to 'metabolic flexibility' and non-POMC pathways.

Acute postexercise elevations in systemic anabolic hormones (testosterone, growth hormone, IGF-1) are neither necessary nor sufficient to stimulate muscle protein synthesis or drive resistance exercise training-induced hypertrophy.

Stop worrying about the exact time of day you train or trying to manipulate your hormones for better gains. Whether you train in the morning or evening, or whether your hormones fluctuate during your menstrual cycle, does not significantly change your ability to build muscle. Focus on consistent, progressive resistance training rather than trying to 'optimize' your hormonal environment.

Exaggerated secretion of GLP-1 following RYGB and sleeve gastrectomy is causally responsible for improved postprandial beta-cell function and glucose tolerance, as demonstrated by the reversal of these benefits when GLP-1 receptors are blocked.

Surgery triggers a natural surge in GLP-1, a hormone that boosts insulin and improves blood sugar control. This hormonal boost is so effective that blocking it reverses the surgery's benefits, confirming GLP-1's central role in diabetes remission.

Niacin is no longer recommended for routine use in type 2 diabetes because large clinical trials failed to show significant cardiovascular benefits despite improving lipid parameters.

Do not use niacin to treat high triglycerides or low HDL in type 2 diabetes. Large studies show it does not reduce heart attacks or death, and it may worsen blood sugar control. Stick to statins and fibrates if needed.

Obesity is a biologic disorder caused by alterations in CNS pathways controlling energy balance, not a lifestyle failure remediable by willpower alone.

Stop blaming yourself for your weight. Your body is fighting you due to biological mechanisms, not just willpower. Seek medical treatment for obesity just as you would for high blood pressure.

GLP-1 therapy is associated with significant gastrointestinal side effects (nausea, vomiting, diarrhea, constipation) which are dose-dependent and can lead to discontinuation, although most side effects decrease with continued use.

You will likely experience some gastrointestinal side effects like nausea, diarrhea, or constipation, especially when you start the medication or increase the dose. These symptoms often improve over time. Talk to your doctor about managing these side effects through diet and slow dose titration.