Many fad diets exist, each one making big promises. For seafood lovers, the tuna diet might be the most tempting - lose 11 kgs in one week, eating nothing but tuna for a few days, and then transitioning to healthy foods after. So we’ve weighed the benefits and dangers of this diet to answer your most pressing questions - how much tuna can you eat safely? This article is intended for general informational purposes only and does not serve to address individual circumstances. It is not a substitute for professional advice or help and should not be relied on for making any kind of decision-making. You should always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or your specific situation. Never disregard professional medical advice or delay seeking it because of content you read online.
What is the Tuna Diet?
The tuna diet is based on the idea that eating only tuna and water can help you lose a lot of weight fast. The reason why this ‘diet’ works is because your body relies on stored energy (fat) for most of its fuel to survive. By getting rid of all carb rich foods off limits from your diet, such as breads, pasta and starchy vegetables, you cut out calories that you would normally use up throughout the day. This is the ‘fish and water’ period. You must only eat tuna, at least 1.5 grams of protein per kilogram of body weight (3.3 grams per lb.) each day. It’s not clear how many days you should eat protein, fruits, and vegetables before starting the 3-day tuna diet again. You can create a plan based on how much weight loss you’d like to achieve.
Nutritional Value of Tuna
First things first, how nutritious is this fish? Tuna is not a fatty fish - it’s overall fat content is low. However, the fat it has is the good type - omega-3 fatty acids that have proven health benefits including protecting against heart disease and stroke, lowering triglycerides, and helping treat depression. Tuna has calcium, phosphorus, potassium, zinc, B-vitamins, selenium, and choline. Each of these nutrients perform important functions in our bodies. Tuna is very high in complete proteins, that is, it has all of the essential amino acids. These are essential for bodybuilding and muscle maintenance. Tuna has no carbs, fiber or sugar. This makes it a great addition to any low-carb weight loss plan.
However, canned tuna can be high in sodium - when you’re eating too much tuna as part of a diet, you need to watch out for this sodium content.
Potential Benefits of the Tuna Diet
In moderation, tuna can be part of a healthy diet. Tuna’s low fat content makes it an ideal choice for anyone looking to lose weight. A calorie deficit is essential for weight loss. Weekly calorie intake depends on a person’s weight and activity level, but 2000 calories is a safe starting point for most men and 1600 calories is a good amount of calories for women. When consumed in moderation, tuna has no adverse effects on cholesterol levels or blood pressure. Amino Acids Methyl-containing amino acids such as taurine are found in a significant amount of fish, especially tuna and cod. This diet restricts your calorie intake, which can help improve your overall weight loss results.
Read also: An In-Depth Look at Bale's Diet
Potential Risks of the Tuna Diet
Despite these potential advantages, the diet’s focus on calorie restriction and a limited variety of “approved” foods raise concerns about its safety, sustainability, and long-term impact on health.
Nutrient Deficiencies
Many high-protein diets, such as the tuna and egg diet, are highly restrictive, limiting complex carbohydrates, healthy fats, and certain fruits and vegetables, as well as the fiber, vitamins, and minerals they provide. This can cause a number of problems, such as headache and constipation.
Too Few Calories for Daily Needs
Diets like the tuna and egg diet are incredibly low in calories, prescribing about 1,100 to 1,400 calories per day. However, to maintain healthy energy levels, adult women need around 1,600 to 2,400 calories per day, and adult men need about 2,000 to 3,000 calories per day.
Unsustainable Weight Loss
Weight loss from the tuna and egg diet comes from its “extreme caloric reduction and rigid eating patterns,” which are unsustainable in the long run. This kind of weight loss is typically water weight, especially when measured in the short term. That’s why people who tend to take this route end up regaining the weight they lost once they complete the diet.
Mercury Exposure
Tuna contains high levels of mercury, a heavy metal chemical element known to alter brain functioning as well as affect growth and development in infants and young children. However, you can limit the amount of mercury you intake by choosing canned light tuna instead of albacore or yellowfin tuna. Food and Drug Administration (FDA) recommends eating a variety of fish instead, including canned salmon and sardines, frozen fish, and fresh fish. If you prefer albacore tuna, also known as white tuna, limit this to one serving per week with no other fish that week. Albacore tuna contains three times more mercury than canned light tuna. Mercury poisoning has been tied to damage to the heart, kidneys, and nervous system.
Read also: Healthy Tuna Salad
However, you will not gain these benefits if you eat too much tuna - overloading on vitamin A from tuna can cause serious damage to your liver.
High Cholesterol Levels
A single egg contains 237 milligrams of cholesterol, almost as much as a 12-ounce beef burger. While most people can safely consume up to seven eggs per week without increasing the risk of heart disease, people living with diabetes or heart disease should be mindful of how many eggs they’re eating, how they’re prepared, and any other cholesterol consumption in their diets.
Potential Kidney Strain
Another risk of high-protein diets may be strain on the kidneys, especially for people with or at risk of impaired kidney function.
Other drawbacks
Rapid weight loss can also have a negative effect on your metabolism. Although this fish is nutritious, it doesn’t have all the nutrients necessary to perform daily activities and keep your body functioning optimally. It doesn’t have carbs, and this can trigger intense cravings that might make it harder to stick to the diet. The problem arises when you continue this diet longer than the recommended 3 days. Long term ingestion of very low calories can affect your metabolism and make it harder for you to lose weight. While eating tuna can be healthy in moderation, going on a fish-only diet is extreme. Tuna is not the only option for weight loss and should not be consumed every day.
Alternative Approaches to Weight Loss
To lose weight and stay healthy without sacrificing your muscle tone, aim for slow and steady results. Don’t be discouraged if the number on your scale doesn’t drop as quickly or drastically as you hoped it would. We’ve established that reducing your calorie intake is the only way to lose weight. Instead of going from three meals a day to living off tuna, a more sustainable approach is to cut down on your meal portions. Eating only what you need, and stopping when you feel full is a skill that is learned over time. When you’re starting out, focusing on counting every calorie and weighing all foods can make the process overwhelming. What works for someone else in terms of portions might not work for you. If you have a carb-sensitive body type, you’ll reduce your carb portions. Mastering your hunger cues prevents emotional eating, ensuring you eat only when necessary.
Read also: Cheesy Keto Tuna Patties
It is best for your health to try other options, such as setting goals to walk more steps each day and consuming fewer calories from fat sources.
If you want to lose pounds and keep them off, one important way is to build muscle mass. To build muscles and raise your metabolism, aim for weight training exercise sessions 3-4 times a week. You should also incorporate cardiovascular exercise into your program two or three days a week in the form of 30 minute brisk walks, jogging or cycling at least 5 miles per day.
The Military Diet: A Similar Restrictive Approach
The military diet (which has no real link to the branches of the military) is a plan that advertises itself as a quick way to lose weight by following a very strict diet plan, with the claim that you’ll lose up to 10 pounds in 1 week. For the first 3 days (your “on” days), you follow a specific diet. Then for 4 days after that (your “off” days), the plan suggests you continue to restrict your calorie count.
The military diet only allows for 1,100 to 1,400 calories a day for “on” days. For “off” days, the plan recommends keeping your calories below 1,500. The FDA recommends adults eat an average of 1,600-3,000 calories a day, depending on age and activity levels. The military diet calorie counts fall well below that number. You need to take in the number of calories your body needs to work well for the long haul.
Certain people may choose to follow the military diet for longer terms (like repeating the diet with 4-days in between). But restricting your calories that drastically over a long period of time isn’t healthy. The military diet makes many claims, including the promise that you’ll lose 10 pounds in 1 week. But every body is different, and everyone loses weight in different ways and at different rates. Always talk to your doctor before trying any new diet, especially one that bans food groups or restricts calories to a small number. The plan is a very strict, low-calorie diet with some foods that seem healthy and others that don’t. There are set foods to eat for breakfast, lunch, and dinner, but that’s it. There are no snacks, and there’s no wiggle room about food choices based on your tastes.
Your calorie count starts at 1,400 on day 1 of your 3 “on” days. Day 2 ramps down to 1,200 calories, and then on day 3, your approved food list and amounts totals only 1,100 calories. The plan does allow 100 extra calories for men a day “preferably in the form of protein, not carbs.” The diet itself only lasts for 3 days. After that, the plan recommends switching to a normal diet but keeping your calories below 1,500 for the next 4 days. The plan also notes you can repeat the program as often as you’d like, if you’d like to lose more weight, as long as you take 4-day breaks every time after you do it.
Every morsel you’ll eat on this diet has been chosen for you ahead of time. You’ll need to follow the plan completely to get the best results.
Foods Allowed and Avoided on the Military Diet
On the list of approved foods you’ll find normal choices, like canned tuna, hard-boiled eggs, and cheddar cheese. At least one meal includes saltine crackers.
It doesn’t include superfoods like salmon, almonds, or quinoa.
You can drink water and black coffee or tea, but no soda, milk, juice, or alcohol. Stick to the menu as much as you can. You’re allowed to switch out some foods if you have food allergies or other dietary needs. But only make swaps that the diet approves. For example, you can have sunflower seed butter instead of peanut butter or a tofu dog instead of a hot dog. But don’t switch the vanilla ice cream to a scoop of mint chip or cookie dough.
Some foods are banned because they aren’t as effective as the specific foods on the plan. You can’t substitute orange for grapefruit, for example, because the grapefruit has a specific pH level and an orange would have the opposite effect. In fact, the plan says if you don’t want to eat grapefruit, you can simply drink 1/2 a teaspoon of baking soda in water for the same effect on your body’s pH levels.
Military Diet Food List
The military diet plan gives you a list of allowed foods to buy at the store before your 3 “on” days. It includes:
- Coffee or tea (caffeinated)
- One grapefruit
- Bananas (2)
- Apples (2)
- Whole-wheat bread
- Peanut butter
- Eggs
- Cans of tuna (3)
- Hot dogs
- Small piece of meat (1)
- Green beans (fresh, frozen, or canned)
- Small head of broccoli
- Carrots
- Saltine crackers
- Cottage cheese
- Small container of cheddar cheese
- Vanilla ice cream
There’s a 3-day menu to follow, with a total of nine different meals. For example:
One breakfast menu requires you to eat:
- 1/2 grapefruit
- 1 slice toast
- 2 tablespoons peanut butter
- 1 cup coffee or tea (no cream or sugar)
One dinner menu includes:
- Two hot dogs without buns
- 1 cup of broccoli
- 1/2 cup of carrots
- 1/2 banana
- 1/2 cup of vanilla ice cream
Pros and Cons of the Military Diet
Every diet has pros and cons. Some diets fit some lifestyles or body types better and some don’t. It’s important to pay attention to what works for you.
In the short term, you will likely lose weight. There’s no way to guarantee how much weight you will lose, but in general, restricting your calories does make you lose pounds temporarily.
When you do very strict “on” and “off” diets like the military diet, it can begin to warp your view of food. If you have to avoid certain foods altogether, or can only follow a very specific list, you’re at risk of developing disordered eating -- an unhealthy relationship with food.
Also, because a restrictive calorie diet isn’t sustainable, eventually you will go back to eating normally. And when your body has been in a “scarcity” mode, it will hang on to any energy it gets, leading to weight gain -- what you lost on the diet and often even more. There are no meetings to attend or packaged meals to buy. The food is easy to find in the grocery store, and there’s very little cooking or food prep needed. But you may feel very hungry on the diet, so you may need willpower to get through 3 days without cheating. You’ll only be eating about 1,500 calories daily, so you may feel more sluggish than usual. If you choose to exercise, it may make you even more tired.
The Military Diet doesn’t ask you to avoid carbs, dairy, or other food groups. You may not want to eat out when you’re on the program, though, because the food choices are very strict, and you probably won’t find them on a normal menu.
While it’s a good idea to exercise every day, don’t exert yourself by running or lifting heavy weights during the 3 days you’re on this low-calorie diet. Light exercise is best, like walking or gentle yoga.
Modifications for Specific Dietary Needs
With some tweaks, most adults can follow the diet:
- Vegetarians and vegans. The plan lists easy swaps for the eggs, tuna, meat, and hot dogs: Have nuts, lentils, tofu, and soy/tofu dogs instead. Vegans can eat nut/tofu cheese instead of cheddar, plus soy ice cream, avocado, hummus, and vegan cottage cheese.
- Gluten-free diet. When the menu calls for toast or crackers, choose gluten-free options.
- Low-salt diet. You can get low-salt versions of all of the processed foods on the menu. Swap saltines for rice cakes or low-salt melba toast.
- Caffeine-free. Some people can’t tolerate caffeine. Although the diet claims to work best with caffeine added to your daily menu, it does allow for herbal or green tea as a substitute.
Recommended Recipes for "Off" Days
After you complete your 3 “on” days, these recipes are recommended for “off” days:
- Mediterranean plate. 1 piece of whole wheat pita bread stuffed with 1 ounce feta cheese, 1 cup of tomatoes, 6 olives, 1/4 cup hummus, and 1 cup raw spinach drizzled with 1 teaspoon of olive oil and 1 teaspoon of lemon juice.
- Vegetarian quesadilla. 1 whole-wheat tortilla stuffed with 1/3 cup shredded Cheddar, 1/4 cup black beans, 1/4 cup each sliced peppers and mushrooms, sautéed in 1 teaspoon olive oil. Serve with 1/4 avocado, sliced.
- Cajun chicken with rice. Sprinkle 1 teaspoon dried Cajun seasoning on 4 ounces of chicken breast. Bake or grill. Sauté 1 clove of garlic, 1/2 cup chopped onion, 1 bell pepper, in 2 teaspoons of olive oil. Add 2 tablespoons of tomato paste and a few sprinkles of Tabasco sauce. Add 3/4 cup of precooked brown rice. Serve the chicken on top of the rice.
Expert Opinion on the Military Diet
While fast weight loss may be possible on the military diet, the promises of the diet aren't backed by research or recommended by nutritionists, says Kathleen Zelman, MPH, RD, LD, a registered dietitian nutritionist. “Fasting diets are probably OK in emergency situations when you're trying to drop weight quickly, but it's definitely not a plan recommended by registered dietitians and nutritionists," as the general recommendation is to lose only 2 pounds a week versus the “up to 10 pounds a week” that is proposed by the military diet plan.
And although the military diet can help you to lose weight quickly, it's not the type of weight that you want to lose. “It will absolutely lead to weight loss; however, it’s not necessarily the fat that you’re trying to burn,” Zelman says. “With these fad-type diets, there tends to be more of a loss of water weight and also lean muscle mass. … So while you’ll see the numbers drop on the scale, you’re losing something that you actually want to protect,” which is your lean muscle mass. Studies show that if you lose lean muscle mass, which commonly happens when you follow a weight loss program with a strict diet, your muscle strength and resting metabolic rate (or, the amount of energy your body needs to work while its at rest) also decreases. This debunks the military diet claim that says the select foods allowed on the diet give you energy and control sugar. "You know what your body does if it thinks it's starving?" Zelman questions. "It thinks, 'OK, I need to turn things down here to compensate because I'm not getting enough calories,' and it slows down your basal metabolic rate." She notes that the impact on your metabolic rate is not positive, and it's a scientific fact.
Effectiveness and Sustainability
The military diet is not sustainable or suitable for long-term use. According to Zelman, trying the military diet for longer periods is something you’re probably not going to want to do. “The reason it's a 1-week diet is because it isn't sustainable," Zelman says. “The 3-day diet is basically a fast followed by 4 days of a very low-calorie diet. You're not gonna want to come back and do this again and again because it's too hard.” The four "on-days," of the diet, where you're allowed more freedom in food choices and up to 1,500 calories daily, is a more attainable goal, Zelman says.
The military diet (and the specific foods allowed on the diet) “isn’t nutritionally complete, and even though multivitamin minerals can fill in nutritional gaps, you’re still not getting enough fiber in this dietary plan," Zelman says. “You don't get the phytochemicals and the kind of good matrix that's found in food. You can't replace that with vitamins or minerals."
The expected calorie count is too low (the general recommendation is a minimum of 1,200 for women and 1,500 for men) and the foods are unhealthy and processed, which can lead to adverse side effects and gaining the weight back and then some in the long run, Zelman says, adding that the diet “defies the recommendations of the dietary guidelines," including restrictions on dairy, fruits, and vegetables.
Suitability for Specific Conditions
The foods allowed on this diet are also usually connected with an unhealthy diet. “Processed foods like crackers and hot dogs might be associated with weight gain and is not part of a heart healthy diet," Zelman says. "Regularly eating processed foods might be associated with various conditions, like gaining weight… and certainly heart healthy diets don't include these kinds of foods," Zelman says, adding, “If you are a person with diabetes, this is not necessarily the type of food that you would eat. So these kinds of foods are associated with some conditions and you don't want to provoke that."
Moreover, specific age groups should steer clear of diets like these. Studies show that the biggest risk of following a very-low calorie diet is possible muscle mass loss, which in turn can increase the risk of declining strength and function. Protecting yourself from this risk is especially important as you age, to decrease the risk of conditions like sarcopenia, which is age-related loss of muscle strength and mass.
The decreased muscle mass and strength that can come from this diet could also have an impact if you have underlying health conditions or are taking certain medications, including loss of strength and reduced energy level. “There aren't any conditions that would support this kind of approach,” Zelman says.
The Bottom Line on Restrictive Diets
The military diet can end in weight loss, but it’s not the way to lose weight. “It's not tackling your lifestyle habits, and not providing a sustainable meal pattern or teaching you anything," Zelman says. "You're not making any kind of headway toward long-term success because anyone who wants to lose weight wants to keep it off, they don't want to gain it back on."
Further, being on the diet could actually promote unhealthy habits. "When you don't get enough calories … the biggest risks are either binge eating, creating an eating disorder, or constipation," Zelman says. "There's just not enough food, period, and it doesn't promote positive long-term habit changes," Zelman says. "You're gonna lose it, you're gonna regain it … so why bother?"
Instead, Zelman recommends that aiming for a weight loss rate of one to two pounds a week "is much more likely to ensure fat loss from fat not loss of fluid or muscle mass."
There are many variables that weigh into your calorie needs, including your age, your genetics, and your physical activity, Zelman says. "Before you do something this drastic, speak with your health care providers or consult a registered dietitian nutrition to make sure that it doesn't contradict what your particular health condition is at the time."
Common Questions About the Military Diet
- How much weight can you lose on a 3-day military diet? The plan states you can lose up to 10 pounds in 1 week; however, the general recommendation is losing up to 2 pounds in 1 week.
- Can you drink alcohol on the 3-day military diet? No. The diet recommends drinking as much water as you can. You're also allowed to have caffeine-free herbal tea and coffee with no added creamer or sugar.
- What happens if you do the military diet for a month? Trying the diet for a month doesn't seem to be the intent, says Zelman. In fact, "the reason it's a one-week diet is because it isn't sustainable," Zelman says. "Essentially it's a fast followed by a 4-day very low-calorie diet. You'll see the numbers on the scale move, but you're not gonna want to come back and do this again and again because it's too hard."
- How much does the plan cost? There are no fees to pay or meetings to join. After you buy your food, you’re set.
- Does the military diet offer support while you’re following it? There are no meetings or official online support groups.
Is It Safe to Follow the Boiled-Egg Diet?
If you have a history of disordered eating, restrictive diets of any kind (including the boiled-egg diet) aren’t for you. Those living with chronic health conditions, especially any that require taking medication, would be wise to check with their healthcare team before making any dramatic changes to their diet - and the boiled-egg diet would count as dramatic.