What is the OMAD Diet?
The OMAD Diet (One Meal A Day) is one of the simplest and most effective forms of Intermittent Fasting (IF).
Instead of eating breakfast, lunch and dinner, OMAD involves consuming no calories for the majority of the day (fasting), and then having one large meal. The timing of this meal can be changed to fit with your lifestyle. Some prefer to have a large breakfast, whilst some prefer to have a large dinner at the end of the day.
This website is your ultimate guide to OMAD. Here you’ll find unbiased, evidence-based information on the pros and cons of eating one meal a day, helping you to decide if it’s the right approach for you.
Disclaimer: This website discusses the many proven benefits of intermittent fasting, but there are potential dangers if you are taking medication. The information on this website is not medical advice. Please discuss any lifestyle changes with your doctor. Those that are under 18, underweight, have an eating disorder, or are pregnant or breastfeeding, should not follow a fasting protocol unless instructed by a medical professional.
What are the Benefits of the OMAD Diet?
OMAD and intermittent fasting have been the subject of a number of studies, revealing a range of health, weight-loss and lifestyle benefits. We’ve included the main OMAD benefits below, or you can read our full list by clicking here.
Improving Cell Function, Genes and Hormones
Periods of fasting reduces the body’s insulin levels, resulting in increased fat burning. It is also associated with cellular repair called autophagy, and gene expression, which has benefits for ageing and disease resistance. [1, 2, 3]
Increased Weight Loss and Muscle Gain
Fasting triggers an increase in growth hormones, assisting with muscle gain and weight loss. Alongside this, lowered insulin levels allow your body to use stored fat as energy.[4, 5]
Reduced Insulin Resistance
Intermittent fasting has been shown to reduce insulin resistance. When an individual reduces their insulin resistance, blood sugar levels typically lower, helping to protect against the effects of type 2 diabetes. Doctors at the Intensive Dietary Management clinic in Canada have proven that intermittent fasting can be used as a method to reduce the symptoms of, and even reverse the effects of type 2 diabetes.[6]
Reduced Inflammation
Studies have shown that short-term fasting reduces inflammatory activity in the body. A recent study by the researchers at the Mount Sinai School of Medicine showed that fasting improves chronic inflammatory diseases without compromising monocyte emergency mobilization. Monocytes are a type of white blood cell important for fighting infections.[7]
No Need to Track Macros
Most people that follow an OMAD diet do not track calories or macros. Although some do, to help hit specific targets of fitness goals, many take a more relaxed approach to intermittent fasting. Since it is difficult to overeat when only eating one meal a day, most simply eat what they feel like on that given day (within reason). This is one of the primary attractions of this type of eating, since no foods are ruled out, although this shouldn’t be used as an excuse to binge on junk food.
Reduced Food Costs
Less food is typically consumed when eating one meal a day. Although many will make their one meal larger to compensate for the lack of food during the fasting period, it is still difficult to eat an equivalent amount to breakfast, lunch and dinner. As such, total money spent on food is lower, especially in the case of snacks and convenience foods.
More Time in the Day
Eating one meal a day means significantly less time is spent on food shopping, cooking and dishwashing. This time adds up, and can be spent on other productive activities, or simply spent relaxing.
What can I eat on OMAD?
When Fasting
When following a 23:1 diet, the majority of the day is spent fasting. This means no calories can be consumed, and includes both food and drink.
Typically any food items will have calories, so should be avoided. However, zero calorie drinks can still be consumed when fasting. This includes black coffee, green tea, and zero calorie soft drinks. Anything that adds calories to your hot drinks (like milk or sugar) can not be included.
It is worth noting that research has shown that some zero calorie artificial sweeteners can cause an insulin response, due to cephalic phase insulin release.[8] This is when your body releases insulin before you digest food, triggered by the sight, smell, and taste of food. This may negate some of the benefits of fasting, and as such we recommend only consuming articial sweeteners in moderation.
When Eating
For your one meal per day (or your one hour spent eating), you can eat whatever feels right. This means you can eat a healthy, balanced meal to help you reach your broader fitness goals, or you can eat the burger and fries you’ve been craving all day. This is one of the main attractions of the OMAD diet.
It is important to note that binging on unhealthy foods could stall weight-loss progress and the health benefits of IF, so whilst you should enjoy your food, you should always remain responsible in your eating habits. The general rule of thumb is to avoid sugar and processed foods if you can, but they’re fine to enjoy in moderation.
Many people like to combine OMAD with low carbohydate diets (like keto), which further compounds some of the positive effects of fasting. This can speed up weight-loss progress, but isn’t essential.
Can I Exercise on an IF Diet?
Exercising whilst following an OMAD diet is encouraged, although you may need to tweak the timing of your meals or workouts.
When in a fasted state, some workouts may be more challenging due to a lack of glycogen in the muscles. When this is the case, it’s usually best to workout within a few hours of eating. This is typically more noticeable with heavy strength workouts or sustained cardio.
Some people enjoy working out in a fasted state, and do not suffer from a lack of energy. If this is the case, working out at any time is fine.
