Insulin is a hormone produced by the beta cells of your pancreas.
It’s secreted in small amounts throughout the day and in larger amounts after meals.
Insulin allows your cells to take in blood sugar for energy or storage, depending on what is needed at the time.
Insulin is also the main fat storage hormone in the body. It tells fat cells to store fat, and prevents stored fat from being broken down.
When cells are insulin resistant (very common), both blood sugar and insulin levels go up significantly.
Here are some tips to normalize insulin levels and improve insulin sensitivity:
- Avoid or minimize sugar: High amounts of fructose and sucrose promote insulin resistance and raise insulin levels (
10, 11, 12, 13, 14, 15).
- Reduce carbohydrates: A low-carb diet can cause an immediate drop in insulin levels (
16, 17, 18, 19).
- Fill up on protein: Protein actually raises insulin in the short-term. However, it should lead to long-term reductions in insulin resistance by helping you lose belly fat (
- Include plenty of healthy fats: Omega-3 fats found in fatty fish can help lower fasting insulin levels (
- Exercise regularly: Overweight women who walked briskly or jogged had an improvement in insulin sensitivity after 14 weeks in one study (
23, 24, 25).
- Get enough magnesium: Insulin resistant people are often low in magnesium, and magnesium supplements can improve insulin sensitivity (
26, 27, 28).
- Drink green tea: Green tea may lower blood sugar and insulin levels (
Insulin is the main fat storage hormone in the body. Reducing sugar intake, cutting carbs and exercise are the best ways to lower insulin levels.
Leptin is produced by your fat cells.
It’s considered a “satiety hormone” that reduces appetite and makes you feel full.
As a signaling hormone, its role is to communicate with the hypothalamus, the portion of your brain that regulates appetite and food intake.
Leptin tells the brain that there’s enough fat in storage and no more is needed, which helps prevent overeating.
People who are overweight or obese usually have very high levels of leptin in their blood. In fact, one study found that leptin levels in obese people were 4 times higher than in people of normal weight (
Unfortunately, in obesity the leptin system doesn’t work as it should. This is referred to as leptin resistance.
In essence, your brain thinks it is starving, so you’re driven to eat.
Leptin levels are also reduced when you lose weight, which is one of the main reasons it is so hard to maintain weight loss in the long-term. The brain thinks you are starving, and pushes you to eat more (
Here are a few suggestions for improving leptin sensitivity:
- Avoid inflammatory foods: Limit foods that cause inflammation, especially sugary drinks and trans fats.
- Eat certain foods: Eat more anti-inflammatory foods, such as fatty fish (
- Exercise regularly: Moderate activity can improve leptin sensitivity (
43, 44, 45).
- Get enough sleep: Studies have shown that insufficient sleep leads to a drop in leptin levels and increased appetite (
- Supplements: In one study, women on a weight-loss diet who took alpha-lipoic acid and fish oil lost more weight and had a smaller decrease in leptin than those in a control group (
People with obesity tend to be resistant to the effects of leptin. Consuming anti-inflammatory foods, exercising and getting enough sleep may improve leptin sensitivity.
Normally, ghrelin levels are highest before eating and lowest about an hour after you’ve had a meal.
Studies have also shown that after obese people eat a meal, ghrelin only decreases slightly. Because of this, the hypothalamus doesn’t receive as strong of a signal to stop eating, which can lead to overeating (52).
Here are a few tips to improve the function of ghrelin:
- Sugar: Avoid high-fructose corn syrup and sugar-sweetened drinks, which can impair ghrelin response after meals (
- Protein: Eating protein at every meal, especially breakfast, can reduce ghrelin levels and promote satiety (
55, 56, 57, 58).
Eating plenty of protein and avoiding foods and beverages high in sugar can help optimize ghrelin levels.
Cortisol is a hormone produced by the adrenal glands.
It’s known as a “stress hormone” because it’s released when your body senses stress.
However, a strict diet can also raise cortisol. In one study, women who consumed a low-calorie diet had higher cortisol levels and reported feeling more stressed than women who ate a normal diet (
These strategies can reduce cortisol levels:
- Balanced diet: Follow a balanced, real food-based diet. Don’t cut calories to extremely low levels.
- Meditate: Practicing meditation can significantly reduce cortisol production (
- Listen to music:. Researchers report that when soothing music is played during medical procedures, cortisol doesn’t rise as much (
- Sleep more: One study found that when pilots lost 15 hours of sleep over the course of a week, their cortisol levels increased by 50-80% (
High cortisol levels can increase food intake and promote weight gain. Eating a balanced diet, managing stress and sleeping more can help normalize cortisol production.
Estrogen is the most important female sex hormone.
It is mainly produced by the ovaries, and is involved in regulating the female reproductive system.
Both very high and low levels of estrogen can lead to weight gain. This depends on age, action of other hormones, and overall state of health.
To maintain fertility during the reproductive years, estrogen starts promoting fat storage at puberty (
Obese women tend to have higher estrogen levels than normal weight women, and some researchers believe this is due to environmental influences (
During menopause, when estrogen levels drop because less is produced in the ovaries, the site for fat storage shifts from the hips and thighs to visceral fat in the abdomen. This promotes insulin resistance and increases disease risk (
These nutrition and lifestyle strategies can help manage estrogen:
- Fiber: Eat plenty of fiber if you want to reduce estrogen levels (
71, 72, 73).
- Cruciferous vegetables: Eating cruciferous vegetables may have beneficial effects on estrogen (
- Flax seeds: Although the phytoestrogens in them are controversial, flax seeds appear to have beneficial effects on estrogen in most women (
- Exercise: Physical activity can help normalize estrogen levels in both premenopausal and postmenopausal women (
When estrogen levels are too high or low, weight gain may occur. This depends on age and other hormonal factors.
Neuropeptide Y (NPY) is a hormone produced by cells in the brain and nervous system.
Recommendations for lowering NPY:
- Eat enough protein: Eating too little protein has been shown to increase release of NPY, which leads to hunger, increased food intake and weight gain (
- Don’t fast for too long: Animal studies have demonstrated that very long fasts, such as over 24 hours, can dramatically increase NPY levels (
86, 87, 88).
- Soluble fiber: Eating plenty of soluble prebiotic fiber to feed the friendly bacteria in the gut may reduce NPY levels (
Neuropeptide Y (NPY) stimulates hunger, particularly during fasting and times of stress. Protein and soluble fiber can help lower NPY.
Glucagon-like peptide-1 (GLP-1) is a hormone produced in your gut when nutrients enter the intestines.
GLP-1 plays a major role in keeping blood sugar levels stable, and also makes you feel full.
Researchers believe the decrease in appetite that occurs immediately after weight loss surgery is partly due to increased production of GLP-1 (
In one study, men who were given a GLP-1 solution with breakfast reported feeling more satisfied and ended up eating 12% fewer calories at lunch (
Suggestions to increase GLP-1:
- Eat plenty of protein: High-protein foods like fish, whey protein and yogurt have been shown to increase GLP-1 levels and improve insulin sensitivity (
92, 93, 94).
- Eat anti-inflammatory foods: Chronic inflammation is linked to reduced GLP-1 production (
- Leafy greens: In one study, women who consumed leafy green vegetables like spinach and kale experienced higher GLP-1 levels and lost more weight than the control group (
- Probiotics: In an animal study, a probiotic supplement increased GLP-1 levels, which led to a reduction in food intake (
GLP-1 can decrease appetite and increase weight loss. Consuming a diet high in protein and greens can help boost your levels.
Like GLP-1, cholecystokinin (CCK) is another satiety hormone produced by cells in your gut (
Strategies to increase CCK:
- Protein: Eat plenty of protein at every meal (
- Healthy fat: Eating fat triggers the release of CCK (
- Fiber: In one study, when men ate a meal containing beans, their CCK levels rose twice as much as when they consumed a low-fiber meal (
CCK is a hormone that reduces appetite and is produced when you eat protein, fat, and fiber.
Peptide YY (PYY) is another gut hormone that controls appetite.
It is released by cells in the intestines and colon.
Strategies to increase PYY:
- Lower-carb diet: You should eat a lower-carb diet based on unprocessed foods in order to keep blood sugar levels stable. Elevated blood sugar may impair PYY’s effects (
58, 107, 108).
- Protein: Eat plenty of protein from either animal or plant sources (
- Fiber: Eat plenty of fiber (
89, 110, 111).
In order to increase PPY levels and reduce appetite, try avoiding processed carbohydrates and eating plenty of protein and fiber.