The 800 calorie diet is a highly restrictive eating plan that should never be attempted without the direct supervision of a registered dietitian. Because this low calorie approach is difficult to maintain over time, it typically has a very low long term success rate.

Daily calorie needs vary by individual, but most adults require between 2,000 and 2,300 calories to maintain a healthy weight. Consuming only 800 calories a day can be significantly harmful to your overall health and well being.

There are much safer and more effective ways to reach your weight loss goals than extreme calorie restriction. You should consult a nutrition professional for a personalized evaluation and a sustainable meal plan that meets your specific needs.

800 calorie diet meal plan

The following sample menu illustrates just how restrictive this eating plan is in practice:

Main meals	Foods	Calories
Breakfast	1 cup of unsweetened coffee + 1 scrambled egg with 1/2 tomato and 2 tablespoons of diced onion + 1 orange	166 cal
Morning snack	1 plain yogurt with 1 tablespoon of oats and 1 tablespoon of chia seeds	128 cal
Lunch	3.5 oz (100g) of grilled fish + 1 large potato and a salad of cooked vegetables (green beans, carrots, and onion) seasoned with 1 teaspoon of olive oil and apple cider vinegar	311 cal
Afternoon snack	3.5 oz (100g) of strawberries	34 cal
Dinner	Salad with 1.7 oz (50g) of grilled chicken, 2 lettuce leaves, shredded carrots, tomato, and onion. Season with 1 teaspoon of olive oil and apple cider vinegar.	169 cal
Total calories		808 cal

Potential risks

Following an extreme calorie restricted diet can lead to several serious health consequences, including:

Yo-yo effect: Because this diet causes rapid weight loss, most people find it impossible to sustain. Once the diet ends, there is a high probability of regaining the lost weight or even gaining more than before.
Increased risk of malnutrition: Consuming so few calories makes it difficult to get enough essential vitamins and minerals. Furthermore, weight loss may be so aggressive that a person can quickly drop from being overweight to being underweight.
Hair loss, brittle nails, and dry skin: These symptoms often occur due to a lack of essential nutrients, such as omega 3 fatty acids, B complex vitamins, and vitamins A and C.
Hormonal imbalances: Severe restriction can disrupt hormone production and ovarian function, potentially leading to irregular periods or amenorrhea (the absence of menstruation) in women.
Fertility issues: Hormonal shifts and a lack of proper nutrients can negatively impact the body's ability to support a healthy pregnancy.
Mood swings, irritability, and depression: Drastically limiting food variety can deprive the brain of nutrients like magnesium, omega 3s, and B vitamins, which are vital for mood regulation. This can lead to decreased serotonin levels and an increased risk of anxiety and depression.
Weakened immune system: Extreme dieting can suppress the immune system, making the body more susceptible to illness and infection.

Other common side effects include low blood pressure, headaches, hypoglycemia (low blood sugar), nausea, chronic tiredness, and fatigue.

How to lose weight in a healthy way

Choosing a varied, balanced, and colorful diet offers far more long term health benefits than any restrictive fad diet.

Focus on making progressive changes, such as reducing your intake of high sugar and high fat processed foods. Instead, increase your consumption of fruits and vegetables and choose high fiber options like whole grain bread, brown rice, and whole wheat pasta.

Proper hydration is also essential; aim to drink 68 to 85 ounces (2 to 2.5 liters) of water daily. This supports healthy weight loss and ensures your body functions at its best.

Finally, try to incorporate regular physical activity at least three times a week. A mix of aerobic exercises, like swimming or running, and strength training is usually the most effective approach.